Exercice 5 :
H = 5 × ( 3 + 4x ) + 6 × ( 7 - 3x )
H = 15 + 20x + 42 - 18x
I = 2x ( 6 - 3x ) + 4x² - 8
I = 12x - 6x² + 4x² - 8
I = 6x² + 4x² + 12x - 8
I = 10x² + 12x - 8
Exercice 6 :
A = 5x² - 3x + 2
a) x = 0
A = 5 × x² - 3 × x + 2
A = 5 × 0² - 3 × 0 + 2
A = 0 - 0 + 2
A = 2
b) x = - 2
A = 5 × (-2)² - 3 × (-2) + 2
A = 20 + 6 + 2
A = 28
c) x = 1
A = 5 × 1² - 3 × 1 + 2
A = 5 - 3 + 2
A = 4
