f(x) = 3 + 2x - x²
0 = 3 + 2x - x²
3 + 2x - x² = 0
- x² + 2x + 3 = 0
x² - 2x - 3 = 0
x² + x - 3x - 3 = 0
x*(x + 1) - 3x - 3 = 0
x*(x + 1) - 3(x + 1) = 0
(x + 1)*(x - 3) = 0
x + 1 = 0
x - 3 = 0
x + 1 - 1 = 0 - 1
x = 0 - 1
x = -1
x = 3
x1 = -1, x2 = 3
f(x) = 3 + 2x - x²
0 = 3 + 2x - x²
3 + 2x - x² = 0
- x² + 2x + 3 = 0
x² - 2x - 3 = 0
x² + x - 3x - 3 = 0
x*(x + 1) - 3x - 3 = 0
x*(x + 1) - 3(x + 1) = 0
(x + 1)*(x - 3) = 0
x + 1 = 0
x - 3 = 0
x + 1 - 1 = 0 - 1
x = 0 - 1
x = -1
x = 3
x1 = -1, x2 = 3