f(x+1) = 16(x+1)² - (x+1) = 16(x²+2x+1) - x - 1
= 16x² + 32x + 16 - x - 1 = 16x²+31x+15
so
f(x+1)-f(x) = 16x²+31x+15 - (16x² - x)
= 16x²+31x+15 - 16x² + x
= 32x + 15
Okay, so we have 20x+5y=-15.
To find y, let's plug in 0 for x, that way we have 20(0)+5y=-15.
Now do 20(0) and we have the equation: 5y=-15
divide both sides by 5 and we get y=-3!
I believe that the answer is A. If you need any help with how to show work I'd be happy to help you in the comments :0 hope this helps!
