May someone please help me? Thanks~!

(2x-1)(-x^2+5x+5)

Question

May someone please help me? Thanks~!

(2x-1)(-x^2+5x+5)

markchernioglo · Answer

I know the answer ,but i need help on how to do it.

yttrium · Answer

I can teach you two methods, the cross multiplication method, or the distributive method. Choose what you want to learn.

markchernioglo · Answer

id like to learn both but first ill do the distributive method. :)

markchernioglo · Answer

Thank you

yttrium · Answer

In distributive method, say we have$$(a+b) (x+y+z) = ax+ay+az+bx+by+bz$$

markchernioglo · Answer

wait so how do i use this with this equation?

markchernioglo · Answer

attachment

markchernioglo · Answer

all the steps but i dont understand it.

markchernioglo · Answer

@Yttrium  please help

markchernioglo · Answer

Could we take this step by step? Tomorrow i have a test and I have to know this too.

yttrium · Answer

Say we have your problem. (2x - 1) (-x^2+5x+5)

markchernioglo · Answer

k

markchernioglo · Answer

so first step look at the problem which in this case is (2x-1) (-x^2+5x+5) I understand that.

yttrium · Answer

|dw:1447138834364:dw| this is the second step, you must distribute 2x to the other factor

markchernioglo · Answer

wait wait wait why to second step?

yttrium · Answer

That  will make 2x (-x^2 +5x + 5)

markchernioglo · Answer

i dont get it.

markchernioglo · Answer

actually i do, so you take away the -1 after the 2x?

yttrium · Answer

You said that the first step is to look at the problem.
And what i said is the first step in the distributive method. I just broke it down

yttrium · Answer

Yes, that is right.

markchernioglo · Answer

k i get it so far

yttrium · Answer

the same method will follow for -1

markchernioglo · Answer

wait for the -1? We just got rid of it though.

yttrium · Answer

So, initially, what we will be having is$$2x (-x^{2} + 5x + 5) - 1 (-x^{2}+5x +5)$$

yttrium · Answer

We didn't remove -1 in our process, i just remove it for you to focus on the process itself. Do you understand me so far?

markchernioglo · Answer

yea now i get it.

markchernioglo · Answer

so we have to write (-x^2+5x+5) twice correct?

markchernioglo · Answer

well it is because you wrote it but why?

yttrium · Answer

We our doing "DISTRIBUTIVE METHOD". Our main objective here is to distribute each term of one of the factor to the whole another factor.

markchernioglo · Answer

ok ok

markchernioglo · Answer

so whats next?

yttrium · Answer

|dw:1447139960975:dw|
We well distribute 2x and -1 to each term of (-x^2+5x+5)