Write the function in vertex form. y=-x^2-8x-9

y = -(x+4)² +7

Step-by-step explanation:

I find it convenient to factor the leading minus sign from the first two terms, then work with what's left.

... y = -(x² +8x) -9

Now, add the square of half the x-coefficient inside parentheses. Add the opposite of that amount outside parentheses.

... y = -(x² +8x +4²) -9 +4²

... y = -(x +4)² +7 . . . . . . . . . rewrite parentheses as a square; collect terms

step-by-step explanation: noo

you never say the total so we cant find the percentage used for petrol

step-by-step explanation: