16.2k views
2 votes
Find the coordinates of any points of intersection between the graphs of y = x^2 – 4x + 2 and y = -x^2 – 8x

1 Answer

4 votes

Answer:

(-1, 7)

Explanation:

First, set both equations equal to each other:

(y = x^2 – 4x + 2) = (y = -x^2 – 8x)

x^2 – 4x + 2 = -x^2 – 8x

x^2 + x^2 – 4x + 2 = -x^2 + x^2 – 8x

2x^2 - 4x + 2 = -8x

2x^2 - 4x +8x + 2 = -8x + 8x

2x^2 + 4x + 2 = 0

2(x^2 + 2x + 1) = 0

x^2 + 2x + 1 = 0

x^2 + x + x + 1 = 0

x(x+1) + 1(x+1) = 0

(x+1)(x+1) = 0

x+1=0

x=-1

y = -x^2 – 8x

y = -(-1)^2 – 8(-1) ==> plug in the x-value back into one of the equations

y = -1 – (-8)

y = -1 + 8

y=7

(-1, 7)

User Ken Shoufer
by
4.6k points