Question

Which graph represents the solutions to this equation?

x2 + 8x = -20

A, B, C, or D?
(See pictures attached)

Answer 1

Explanation:

The answer is Graph B.

First the equation needs to be in standard form.

x² + 8x= -20

becomes y = x² + 8x + 20

The leading coefficient is positive - a positve one is in front of the x.

So the parabola opens upward.

solve for the x coordinate of the minimun by using the formula

x = -b/2a

x = -8/2(1) = - 8/2 = -4

substitute -4 into the original equation.

y = (-4)² + 8(-4) + 20

y = 16 + -32 + 20

y = -16 + 20

y = 4

so the minimun - or bottom of the parabola is (-4, 4)

Correct choice is graph B