bonjour
f(x) = (x + 4)(x - 4) - (x + 4)(-6x + 9)
f ( x) = x² - 16 - ( - 6 x² + 9 x - 24 x + 36 )
= x² - 16 - ( - 6 x² - 15 x + 36 )
= x² - 16 + 6 x² + 15 x - 36
= 7 x² + 15 x - 52
f (x) = ( x + 4 ) ( x - 4+ 6 x - 9 )
= ( x + 4 ) ( 7 x - 13 )
f (0) = - 52
f ( x ) = - 52
7 x² + 15 x - 52 = - 52
7 x² + 15 x = 0
x ( 7 x + 15 ) = 0
x = 0 ou - 15/7
f ( - 4 ) = 7 ( - 4 )² + 15 * - 4 - 52 = 112 - 60 - 52 = 0
f (x) = 15 x - 3
7 x² + 15 x - 52 = 15 x - 3
7 x² + 15 x - 15 x = - 3 + 52
7 x² = 49
x² = 7
x = √7 ou - √ 7
