e)
-9x² + 1
x² >=0 | * (-9)
-9x² <=0 | +1
-9x² + 1 <= 1
f) -x² - x + 1
-(x² + x - 1) = -(x² + 2 * x * 1/2 + (1/2)² - 1/4 -1)
-(x+1/2)² + 5/4 <= 5/4
g) -x² -3x - 1
-(x² + 3x + 1) = -( x² + 2 * x * 3/2 + (3/2)² -9/4 +1)
-(x+3/2)² + 5/4 <= 5/4
h) 5x - 3x²
-3x² + 5x = -(3x² - 5x) = - ( (V3x)² - 2* (V3x) * 5/(2V3) + 25/12 - 25/12)
= - ( V3x - 5/2V3)² + 25/12 <= 25/12
