Question

Sonia graphs the equations y = –x2 + 4x and y = x – 4 to solve the equation –x2 + 4x = x – 4. Her graph is shown below.

Answer 1

Answer: C -1 and 4

Explanation:

Edge

Answer 2

C.–1 and 4

Explanation:

Solving the equations y = –x² + 4x and y = x – 4

–x² + 4x = x – 4

x² - 4x + x = 4

x² - 3x = 4

x² - 3x + (3/2)² = 4 + (3/2)²

(x - 3/2)² = 4 + 9/4

= 6.25

x - 3/2 = √6.25 or x - 3/2 = -√6.25

x = 2.5 + 1.5 x = -2.5 + 1.5

= 4 = -1