rewrite in standard form -x^2-2x+15

Question

-x²-2x+15

Answer 1

-x²-2x+15=0 would be the standard form of a parabolic equation. I assume they instead want you to have it in vertex form.

 

In this case you would factor the equation, getting:

-(x-3)(x+5)=0

Answer 2

The factors of 15 are: 3 and 5.

Note:

the x² is negative (so one of the Xs needs to be negative)

we have a negative 2x

but the 15 is positive

so our components are:

x, -x, -3, and -5 (negative times a negative makes a positive)

 

So far, we have:

(⁺/_-x - 3) (⁺/_-x - 5)

 

Again, since we have a negative 2x, we need a 3x - 5x, and neg * neg = positive, giving us:

-x * -3, and x * -5

 

This means the -x has to be in the other parenthesis set than -3, and x in the opposite of -5:

(x - 3) (-x - 5)

 

We can also factor out the negatives out of -x - 5 (essentially multiplying by -1) , making -(x + 5)

 

So the other way to write this would be:

-(x - 3) (x + 5)