Answer :
y = x² - 5x - 4
y = -2x
-2x = x² - 5x - 4
+ 5x + 5x
3x = x² - 4
0 = x² - 3x - 4
0 = x² - 4x + x - 4
0 = (x + 1)(x - 4)
0 = x + 1 or 0 = x - 4
- 1 - 1 + 4 + 4
-1 = x 4 = x
y = -2x
-2x = x² - 5x - 4
+ 5x + 5x
3x = x² - 4
0 = x² - 3x - 4
0 = x² - 4x + x - 4
0 = (x + 1)(x - 4)
0 = x + 1 or 0 = x - 4
- 1 - 1 + 4 + 4
-1 = x 4 = x
