# Thread: Parabola

1. ## Parabola

The term that needs to be added to y=x^2+8x to make it a perfect square is?

a) -8
b) 4
c) 8
d) 16
e) 64

2. Originally Posted by iorga
The term that needs to be added to y=x^2+8x to make it a perfect square is?

a) -8
b) 4
c) 8
d) 16
e) 64
Im not sure what you call the theorem in English, but it basically involves the following:

$c = (\frac{b}{2})^2$

So c = 16.

$y = x^2+8x + 16$

$y = (x + 4)^2$