bonjour
f(x) = 9 ( x - 2)² - 4
1) ( x - 2)² = x² - 4 x + 4
9 ( x - 2)² = 9 ( x² - 4 x + 4) = 9 x² - 36 x + 36
2) 9 ( x - 2)² = [ 3 ( x - 2)]²
3) f(x) = [3 ( x - 2)]² - 4 = ( 3 x - 6 - 2 ) ( 3 x - 6 + 2) = ( 3 x - 8) ( 3 x - 4 )
4) f(0)
expression 1 f(0) = 9 ( 0 - 2)² - 4 = 9 *4 - 4 = 36 - 4 = 32
expression 2 : f(0) = 36
expression 3 : f(0) = - 8 * - 4 = 32
f(x) = 0
( 3 x - 8) ( 3 x - 4) = 0 donc x = 8/3 ou 4/3
