C = A - B
= 9x² + 42x +49 - (25-20x+4x²)
= 9x² + 42x +49 - 25 +20x -4x²
C = 5x2+62x+24
C = A - B
= (3x+7)² - (2x-5)²
= [(3x+7) + (2x-5)][(3x+7) - (2x-5)]
= (3x+7 + 2x - 5) ( 3x+7 - 2x+5)
C = (5x + 2) (x + 12)
Pour x = 0
C = 5x2+62x+24
C = 24
Pour x = -1
C = (5x + 2) (x + 12)
= (5 × (-1) + 2) ((-1) + 12)
= (-5 + 2) × (11)
= -3 × 11
C = -33
Pour x = -1/2
C = (5x + 2) (x + 12)
= (5 × (-1/2) + 2) ((-1/2) + 12)
= (-5/2 + 4/2) (-1/2 + 24/2)
= (-1/2) × 23/2
C = -23/4
C = (5x + 2) (x + 12)
= (5√3 + 2)(√3 + 12)
= 5√3 × √3 + 60√3 + 2√3 +24
= 5 × 3 + 60√3 +2√3 +24
= 15 + 24 + 60√3 +2√3
= 39 + 60√3 +2√3
C = 62√3 + 39
C =0
C = (5x + 2) (x + 12)
(5x + 2) (x + 12) = 0
⇔ (5x + 2) = 0 x +12 = 0
5x = -2 x = -12
x = -2/5
