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2014-03-29T02:09:53+01:00

Exercice1.
a) (x+5)² = x² + 10x + 25

b) (y-4)²= y²- 8y +16

c) (t+7) (t-7) = t²-7² = t² - 49

d) (1-10x) (1+10x) = 1 - 100x²

e) (y-6)² = y² - 12 y + 36

f) (a+8)² = a²+16a+ 64

g) (5-9y) (5+9y) = 25 -81y²

h) (x+3) (x-3) = x²- 9

Exercice 2

1. a) développer l'expression (x-1)²=  x² - 2x +1² = x² -2x +1

b) justifier que 99² =9801

(100-1)² = 100² -200+1² = 10 000-200 +1 = 9800+1= 9801

2. a) développer (a-1) (a+1) = a² + a - a - 1 = a² - 1²

b) justifier 99 x 101 = 9999(100-1) (100+1) = 100² - 1²= 10 000 -1 = 9 999