Saturday, September 5, 2009
3x-9>4
3x-9<-4 3x-9>4 <----These are the two equations you will make. Notice how I changed the
3x<5>13 sign on the second one.
x<5/3>13/3
-7x-12<9
-7x<21
x>3 <----Since there was a negative to divide by the sign changed in the final answer.
One thing I didn't understand about inequalities was when theres an equation with fractions.
Don't you have to find the CGF? but I don't understand what to do after that. I think you have to multiply that by the fraction on both signs of the > sign. I don't know, I'm confused. Someone explain please.
Friday, September 4, 2009
Reflection #3
3x-1>2
You just add one to both sides...3x>3... and then you divide by three on both sides...x>1... and that is your answer. But you have to remeber if you multiply or divide by a negative number, then you have to switch the signs. For example,
-2x+1>3
You would subtract one from both sides...-2x>2 and then you would divide by negative two...x<1...>
Reflection #3
l3x-9l>4
Step 1:is it and or or
or
Step 2: when solving and there is an absolute value you must have two equations
3x-9<-4 or 3x-9>4
Step 3:solve for x.
x<5/3>13/3
**but when you divide by a negitive you must change your inequaitie sign**
one thing i didn't seem to get a hold of today was the domain and range. i don't understand how you get a number? i also don't understand when you use infinity.
Wednesday, September 2, 2009
Tuesday, September 1, 2009
Inequalities question?
here's the problem:
4/3 (x - 1/2) + 1/2x > 2/3 (2x - 5/2)
**and by the way, thats ^^supposed to be greater than or equal to. i don't know how to type that. hah
Well anyway, the first thing I did was distribute the 4/3 and the 2/3 but then I don't know what to do with all the fractions after that. I get kinda confused so some help would be good :)
Monday, August 31, 2009
Reflection #2
Well, I understand how to do the rational root theorem.
ex. x4 + 2x3 – 7x2 – 8x + 12
factors of p(constant)=+/-12, +/-1, +/-6, +/-2, +/-3, +/-4
factors of q(leading coeff.)=+/-1
Find p/q=+/-12, +/-1, +/-6, +/-2, +/-3, +/-4
Plug all possibilities into table on calculator and find all where y is 0.
You should get 1, 2, -2, and -3.
Do cythetic division with any two.
1 1 2 -7 -8 12
1 3 -4 -12
1 3 -4 -12 0
(x^3+3x^2-4x-12)(x-1)
2 1 3 -4 -12
2 10 12
1 5 6 0
(x^2+5x+6)(x-1)(x-2)
Solve by factoring x^2+5x+6=
(x+2)(x+3)
x=-2, -3, 1, 2
Put in point form:
(-2, 0)(-3, 0)(1, 0)(2, 0)
Now for what I don't understand! Much easier.
I don't understand how to do the word problems. (Like the one problem with the barn and area and...??) I pay attention when she explains it in class, but I still don't know what I'm doing. Could anyone explain?
Sunday, August 30, 2009
Reflection #2
I'm still trying to catch up actually....
So far, i'm really comfortable with synthetic division so let me try to explain this....
Synthetic division is strictly used to find zeroes or roots of polynomials.
Equation: (x
First you'll set x+3=0
x=-3
this gives you what to synthetically divide by(not sure if that's the correct way to say that! lol) :
-3|1 1 2 5 -3 6
1st: Bring your first number down.
------------------
1
2nd: multiply the number at the bottom by the number being divided and add.
-3|1 1 2 5 -3 6
| -3 6 -24 57 -162
---------------------------
1 -2 8 -19 54 -156
Remainder for this equation would be:
R= -156.
All in all,
these are the steps in words...
- Bring down the 1.
- Multiply it by the -3 to get -3.
- Add 1+-3 to get -2.
- Multiply -2 times -3 to get 6.
- Add 2 plus 6 to get 8.
- Multiply 8 times -3 to get -24.
- Add 5 plus -24 to get -19.
- Multiply -19 times -3 to get 57.
- Add -3 plus 57 to get 54.
- Multiply 54 times -3 to get -162.
- Add 6 plus -162 to get -156.
Now what i don't understand:
I have no idea how to come up with an answer for the Rational root theorem.
I can't figure out my notes for the Calc commands either?
I'm confused after i find the multiples of each,
where do i go from there?(Rational Root theorem)
I have read, reread, and reread again all of my notes. (including the insane amount of sidenotes i took from discussion) and i am still completely lost.
Of course, missing school doesn't help either but i'm really uncomfortable and if anyone has the EXACT calc commands please let me know.
here's what i wrote in my notes:
Y=
enter equation.
2nd mode(quit)
2nd, graph
2nd ZOOM?
2nd TRACE?!
I don't exactly know where i'm getting all of this from?
am i right? wrong? insane? lol.
any form of advice would be beneficial to me,
please&thanks! :)
1st make sure the problem is factored all the way.
y = (x+1)(x-2)(x-4)
2nd take the roots and make a number line with a number between each root.
<----1---0---+2----+4--->
3rd find out for the sketching the positives and negatives
x(-2)neg,neg,neg= Negative
x(0)pos,neg,neg= Positive
x(3)pos,pos,neg= Negative
x(5)pos,pos,pos= Positive
4th put the original points on a graph
Graph -1, 2, and 4
5th sketch the graph by using the positives and negatives to know which way the lines should go
It should go negative, positive, negative, positive.
***********************************************************************
I know how to do the sketching on paper and on the calculator, but I do not know of the buttons to press on the calculator that will give me the max and min. Because I rember something about going left and right on the graph after you get to the max and min screen. Can somebody help me?
reflection 2
step 1. make yourself a little box and stick -2 in it ( it's -2 bec. when you set x+2=0 that is your answer)
step 2. take all of your coefficents and put the on the side in a line.
-2 3 1 0 -3
step 3. bring down your 3 and multiply it by -2 your answer is -6 after that take the -6 and put it right under the 1 and add giving you -5. That then drops down and you multiply -5 by -2 giving you 10. repeat thru -3
-2 3 1 0 -3
-6 10 -20
3 -5 10 -23
step 4. finally the remainder is -23.
if anyone can help with explaining when to use factor by grouping, or the root theorem that would be helpful. thanks.
Reflection #2
2x^4+x^2+7x+1=0
You press the Y= button on you calculator and type the eqation in. (make sure that you type everything in right)
First, you take the roots of the constant (p) and then the leading coefficient (q).
You would get p= +-1 then you would have q= +-2 +-1. Then you have to make p/q.
Possible roots: 1/2, -1/2, 1, -1
Then you plug all of your roots into your calculator. (hit 2nd, Graph) and it brings you to the table. Whatever number(s) you plug in and you get zero, use those numbers.
Next, you use synthetic division. You use the number(s) in the table that gave you zero.
Once you use synthetic divison, you should get all of the roots and your problem should be done.
___________________________________________________________________
Another thing that i learned this week was how to sketch a polynomial function.
y=(x+2)(x-1)(x+3)
1. The first step is to factor completely. (done)
2. The second step is to find your zeros and set up a number line.
x= -2 x=1 x=-3 <---(-3)(-2)-----(1)--->
3. The third step is to plug in any number on both sides of the roots.
f(-4)= -ve -ve -ve = -ve
f(-2.5)= -ve -ve +ve = +ve
f(-1)= +ve -ve +ve = -ve
f(2)= +ve +ve +ve = +ve
4. The fourth step is to sketch your graph. +ve are above the x axis, and -ve are below the x axis.
5. Plug in your calculator to see if your graph is correct.
6. You find your max. and min. in your calculator.
____________________________________________________________________
The thing that i thought was more difficult to learn was the other 2 was to solve a quadratic. I didn't really grasp the concept of how to do quadratic form and grouping. I kind of have an idea of how to do both of them, i just get lost in the middle of their steps. I wish that we would have spent more time on both of those methods, but other than that, chapter two was pretty easy.
Reflection #2
Reflection #2
Given this equation: y=(x+1)(x-1)(x-2)
Step 1: factor the problem completely-done
Step 2: graph the completely factored equation on a number line and lable your zeros
Step 3: plug in numbers on either side of you zeros
Step 4: +ve-above x-axis
-ve- below the x-axis
Step 5: plug in your original equation into y= in your calculator and check your graph.
To find the maximum and minimum:
Step 6: you can only use your calculator
Quadratic maximum and minimum
Step one: x=-b/2a the vertes is always your maximum or minimum
Something I had trouble learning is how to solve anything bigger than a quadratic:
I don’t under stand how you start off with x^4-7x^2-8=0 and get g^2-8g-8=0?
How does the equation start off with the leading coefficient a number raised to the 4th but ends up being a number raised to the 2nd?
Reflection 2
Reflection 2
Sketching Polynomials:
1) Factor completely
2) Set up a number line and label zeros
3) Plug in numbers on either side of your roots
4) +ve=above the x axis
-ve=below the x axis
5) use the calculator to check results
6) find the max. and min. in calculator only
ex: y = (x+1) (x-1) (x-2)
1)done
2) -1,1,2
3)f(0)= +ve
f(1 1/2)=-ve
f(3)=+ve
max-(-.215 , 2.113)
min-(1.549 , -.631)
Rational Root Theorem:
1) Find all possible roots p/q p=factors of the constant
q=factors of the leading coefficient
2) Check to see which roots work in the table
3) Use synthetic division to factor the working roots
4) Solve the quadratic
Ex: x^3 +5x^2 -4x - 20=0
(x^3 + 5x^2) - (4x + 20)
(x^2 - 4) (x + 5)
x= -4 , +-2 , -5
reflection #2
Reflection #2
How to sketch the graph of a polynomial function:
1) Make sure the equation is factored completely. This may be done for you already but if it is'nt you MUST factor or the process won't work.
2) Draw a simple number line and on it label your zeros(roots, x ints., its all the same)
3) Now what you want to do is take a number on both the positive and negative side of your roots on the number line, and plug them into the polynomial function. When you do this, you do not have to actually multiply the number. The important thing is to keep track of negatives and positives. For example:
Say you need to plug 2 into (x-5)(x+2)(x-1)
Instead of worrying about adding and subtracting, you would plug it in and write down this:
-ve x +ve x +ve = -ve
4) Sketch a graph by placing your x-intercepts on a graph, then follow what you plugged in (previous step) to see where you will be above or below the x axis:
+ve = up
-ve= down
5) Plug the equation in the y= on your calculator and press graph to check yourself, if you graph looks similar to the graph on your calculator, you're good!
6) Find Minimum and Maximum in your calculator.
___________________________________________________________________
My only problem this week with not understanding something was with word problems. It was'nt that I didn't know the steps to follow but I get to a certain point where I have the information I need and I just can't figure out what I need to do with this information. The more I see them done the better it is getting though so I think the answer is just keep practicing them and applying what i know.
Reflection#2
Reflection 2
Rational Root Theorem:
1.) Find all possible roots where p is all factors of the constant; q is the factors of the leading
coefficient; p/q.
x^3-x^2-x+1
p=+ or - 1
q=+ or - 1
p/q= 1, -1
2.) Check to see which roots work in the table.
Calculator steps:
+ Click y=
+ Plug the problem into calculator.
+ Click 2nd mode(quit).
+ Click 2nd graph.
+ Plug in all possibilities in the x column.
+ Once possibilities are found, click 2nd mode(quit) again.
3.) Do synthetic division to factor all roots that work.
1 1 -1 -1 1
1 0 -1
_________
1 0 -1 0
4.) Solve the quadratic.
(x-1)=0 (x^2-1)=0
x=1 x^2=1
x= + or - 1
(1,0) (1,0) (-1,0)
I then seemed to find that the most trouble I had with Chapter 2 was the word problems. I understood the formulas for Area and Volume: A= l X w V= l X w X h but I still had trouble working out these problems.
Overall, Chapter 2 was a hard chapter to grasp and hopefully I will understand the next chapter a little better.
Reflections 2
Well this past week was a little more difficult than last week. There was more material to learn and I didn’t study as much as I should have. I knew everything when we were going over it in class however, when it came to the test my mind went blank. Here are a few of the things that gave me trouble on the test: Finding a quadratic when given the roots. Say the roots were
Step 1: find the sum of the roots:
Step 2: find the product of the roots: (
Step 3: Write the equation: x^2 – (sum) x +product=0
Therefore, the equation will be:
The sum of the roots of a polynomial = -2nd coefficient/leading coefficient
The product of the roots of a polynomial are: If the degree is even= constant/leading coefficient
: If degree is odd = -constant/leading coefficient
For example: 6x^3-9x^2+X=0
The sum of the roots= 9/6= 3/2
The product of the roots= -0/6=0
Reflections # 2
Rational Root Theorem:
Example problem
3x^3 - 5x^2 + 5x - 2 = 0
You must find p/q. P is the factors of the constant, and q is the factors of the leading coefficient.
P (factors of -2) = +-2, +-1
Q (factors of 3) = +-3, +-1
p/q = +-2/3, +-2, +-1/3, +-1
Now go to y = in your calculator and plug in the equation. Hit 2nd Graph, and plug in the p/q's to find the right possibility. Once a factor = 0, it is correct, and you can use it.
So if you plug in 2/3, your y should = 0.
Now you use synthetic division and divide the equation by 2/3.
2/3
3 -5 5 -2
2 -2 2
3 -3 3 0
So the new equation is 3x^2 - 3x + 3 = 0
Divide everything by 3. Then use the quadratic formula to solve for the remaining roots.
x^2 - x + 1
x = -b +- the square root of b^2 - 4ac all over 2a
x = 1 +- sqrt of 1 - 4 (1)(1) all over 2 (1)
x = 1 +- sqrt of -3 all over 2
x = 1 +- (i) sqrt of 3 all over 2
x = 1/2 +- i sqrt of 3 over 2
So the final roots are (1/2 + (i) sqrt of 3 over 2, 0)
(1/2 - (i) sqrt of 3 over 2, 0)
(2/3, 0)
reflection 2
One thing that I understand and can teach people how to do it if they don't understand is to sketch polynomial funtions.
If you have y=(x+1)(x-1)(x-2)
1. check if its factored completly
2. set up a number line..
-1, 1, 2
<-------------------------->
-1 1 2
3. f(-2)- neg-neg-neg=neg
f(0)- pos-neg-neg=pos
f(1.5)- pos-pos-neg=neg
f(3)-pos-pos-pos=pos
4. then draw your graph, can't really do that on here..ha
5. plug your equation into your calculator and check to see if your graph is correct
6. then find the max and min, which again..can't do that on here..
If anyone can help me with the quadratic form g thing let me know:)
Reflections 2
So, back to math.
One thing that i did understand easily this week was the part of the chapter where it said factor by grouping.
ok, so take x^3 + 5x^2 - 4x - 20 = 0
to do this problem, first, group the terms (x^3 + 5x^2) - (4x - 20) = 0
then, reduce the terms (or whatever it's called) so that x^2 (x + 5) - 4 (x + 5) = 0
then, regroup the terms outside of the parenthesis so that (x^2 - 4) (x + 5) = 0
then, take the two groups and solve for x x^2 - 4 = 0 and x + 5 = 0
x^2 = 4 and x = -5
x = ±2
then, put your answers in point form (-2,0) (2,0) (-5,0)
then, you're done
But one thing that i didnt get too quickly and need a little bit more help with is problems that you have to find area and you have to draw a box most of the time and all that stuff. I really get confused with that kind of stuff.