bonsoir
a. x ² = x vrai si x = 0 ou 1
b. (x + 3) ² + x ² = 2x ² + 6x + 9
( x + 3 )² + x² = x² + 6 x + 9 + x² = 2 x² + 6 x + 9
c.(x - 1)(x - 2)(x - 4) = x³ - 5x ² + 8x - 4
( x² - 2 x - x + 2 ) ( x - 4 ) = x³ - 4 x² - 2 x² + 8 x - x² + 4 x + 2 x - 8
= x ³ - 7 x² + 14 x - 8
d.2x ² - 8x + 15 = 2(x - 2) ² + 7
2 x² - 8 x + 15 = 2 ( x² - 4 x + 4 ) + 7
2 x² - 8 x + 15 = 2 x² - 8 x + 8 + 7
2 x² - 8 x + 15 = 2 x² - 5 x + 15
e.(x + 5)(x - 3) = (x + 1) ² - 16
x² - 3 x + 5 x - 15 = x² + 2 x + 1 - 16
x² + 2 x - 15 = x² + 2 x - 15
