I need help with this last question. It is still Subtracting Polynomials.

Subtract 10x^3+4x^2+(-7) from -2x^3+9x^3+(-2x)

Question

I need help with this last question. It is still Subtracting Polynomials.

Subtract 10x^3+4x^2+(-7) from -2x^3+9x^3+(-2x)

savvy · Answer

did you try using parenthesis....

anonymous · Answer

Yes, I also tried doing what you did, but it keeps on saying wrong answer. Dx I don't know why, but it tells me it needs to be a positive answer.

savvy · Answer

ok type here wat u did...

anonymous · Answer

(10x^3+4x^2-7)-(-2x^3+9x^2-2x)
(10x^3+4x^2-7)+(2x^3-9x^2+2x)
10x^3+4x^2-7+2x^3-9x^2+2x
12x^3-5x^2-7+2x

savvy · Answer

dude the question says "SUBTRACT 10x^3+4x^2+(-7) FROM -2x^3+9x^3+(-2x)"....you've done the opposite....

anonymous · Answer

D: Oh...

anonymous · Answer

So then it would be,
(10x^3+4x^2-7)-(-2x^3+9x^2-2x)
10x^3+4x^2-7+2x^3-9x^2+2x
12x^3-5x^2-7+2x

savvy · Answer

what is the difference...???
i meant that you have to do this...:
(-2x^3+9x^2-2x) - (10x^3+4x^2-7)

anonymous · Answer

And then I combine like terms?

savvy · Answer

yeah....

anonymous · Answer

Thank you!

campbell_st · Answer

the easy way to do this question is to simply multiply 

$$10x^3 + 4x^2 -7 $$

by negative 1 and add

$$(10x^3 + 4x^2 - 7) \times -1 = -10x^3 - 4x^2 + 7$$

now you have 

$$-2x^3 +9x^2 -2x -10x^3 - 4x^2 + 7 = -12x^3 +5x^2 -2x +7$$