math help

[honda06si]

can someone explain how to do this???

it says factor the trinomial completly

7x^2 + 16x + 4



^2 means x is to the 2nd power

[SiLover]

here u go man

7x^2+16x+4

(7x+2)(x+2)

x= -2/7
x = -2

[honda06si]

Originally Posted by SiLover

here u go man

7x^2+16x+4

(7x+2)(x+2)

x= -2/7
x = -2

so you got that how??? you take the factors of 4.....1,4 and 2,2 and then factors of 7....1,7 and then just sub them in the parenthesis?

[Way2Short]

do FOIL


First, outer, Inner, and Last

[honda06si]

Originally Posted by Way2Short

do FOIL


First, outer, Inner, and Last

i know how to do that but its doing it backwards...it confuses me

[Way2Short]

what you mean?

7x X x=7x^2
7x X 2=14x
2 X x = 2X
2X2=4

=====7x^2+16x+4

[honda06si]

sooo

8x^2+6x+1


answer is (4x+1)(2x+1) ?

[jonebone]

Yes, I got excited when I saw math in the title, as I thought this would be moderately hard. I'm not saying your dumb (a lot of people have problems with factoring when they first learn it), but I expected at least some integration or some type of calculus

Ahh, having a Bachelors degree in Math and not being able to use it, sigh.

[NewDanger]

Originally Posted by honda06si

sooo

8x^2+6x+1


answer is (4x+1)(2x+1) ?

correct

[honda06si]

Originally Posted by jonebone

Yes, I got excited when I saw math in the title, as I thought this would be moderately hard. I'm not saying your dumb (a lot of people have problems with factoring when they first learn it), but I expected at least some integration or some type of calculus

Ahh, having a Bachelors degree in Math and not being able to use it, sigh.

sorry!!!!

yes im a freshman in college and am in math 012......im actually good at math, but that year and a half off of school, i lost my memory

[honda06si]

You have given out too much Reputation in the last 24 hours, try again later.



i will get u guys when i can give rep again

[SiLover]

JUst break it down in your head. What times what equals 7.....umm 7 and 1 and what makes x^2 only x times x.
So we already have (7x )(x )...
Then what times what equals four i chose 2 times 2 because it was the first thing that came to my head.
So now we have (7x 2)(x 2)
In the original equation you had 7x^2+16x+4 so the +4 tells us that either the signs are both going to be + or both are going to be -,and since we have +16x that means we have + signs in both parenthases.

So now we have (7x+2)(x+2) NOw just solve for x..

I Hope this makes sence, becuase it does in my head LOL

[SiLover]

LOL!!!! yeah i saw math in the title and said forget work let me do some math LOL!!!!

[spocheld]

Originally Posted by honda06si

sorry!!!!

yes im a freshman in college and am in math 012......im actually good at math, but that year and a half off of school, i lost my memory

you're doing that in college I did that in 8th grade, LOL!

[jonebone]

Originally Posted by SiLover

LOL!!!! yeah i saw math in the title and said forget work let me do some math LOL!!!!

Lol, you and me both. Just cuz I'm bored:
The derivative of 7x^2 + 16x + 4 is 14x + 16

and the integral is 7/3 x^3 + 8x^2 + 4x + C (C is the constant of integration)

Maybe its over some people's heads, but thats elementary calculus if anyone cares :)

[honda06si]

Originally Posted by spocheld

you're doing that in college I did that in 8th grade, LOL!

whats your address ill send you a frekin cookie

[honda06si]

so is this one prime?

20x^2-20x-15=


edit--- i got 5(4x^2-6)(2-3)

[SiLover]

20x^2-20x-15

(10x-15)(2x+1)

x=15/10 or 3/2
x = -1/2

DOOD are we going to do all of your HW for ya!!!!

[Yodums]

You should get the concept down first, rather than doing it by trial and error.

The first step would be to make sure the equation is correctly arranged, beginning with the highest degree and ending in a constant (if necessary).



You'll notice the first term is the highest degree and it's in a descending order where c is just some constant with no variable attached to it. For this particular example, there is no coefficient (number) in front of the first term, so your factor would look something like this (k is some constant/number):



Both brackets will begin with the variable, x.

Next, the k's or constant will:

1) Have a product (multiply) equal to c (refer to the first diagram - last/third term).
2) Have a sum (added together) equal to whatever bx is (second term of the first diagram).

To make it a little easier, let's use an example with numbers:



What two numbers:

1) Multiply together to give you positive 6
2) Add together to give you negative 5?

Answer is -3 and -2. Since there is no coefficient in front of the first term, you can just stick it in the brackets and go away with it:



If there's a constant in front of the first term which has the highest degree, then you will have to go through a method of trial and error.

For example:



There's a 3 in front of the term with the highest degree, so we can't apply what I initially wrote.

Instead your brackets would look like:



a * c = 3x^2 -----> The first term in the original equation
b * d = 2 ---------> The third term in the original equation

When figuring out numbers, the "bx" term no longer matters.

So what choices do we have for a and c? 3 is a prime number, so it has to be 3 * 1.



The next step would be finding the second terms of both brackets that would give you 2. Let's try -2 and -1.



Well, it didn't work... the method is called trial and error, so let's try switching positions of the -2 and -1 from each bracket:



I hope that helps. Again, get the concept down and then do problems. It would be a mere waste of time to just swap numbers in and out till they work.

[SiLover]

DAMN Yodums you broke it down......or was that a copy and paste job?