Question

quanto é:
(y - 7) . (y + 1) = y2 + 5 =

Answer 1

(y - 7) . (y + 1) = y² + 5 y² - 7y + y - 7 = y² + 5 
y² - 6y - 7 -y²= 5
- 6y = 5 + 7
- 6y = 12
y = 12/-6
y = -2