bjr
h(x) = (x-2)² - (3x+1)²
réflexe.. a² - b² = (a+b) (a-b)
donc
h(x) = [(x-2) + (3x+1)] [(x-2) - (3x+1)]
h(x) = (x - 2 + 3x + 1) (x - 2 - 3x - 1)
h(x) = (4x - 1) (-2x - 3)
si x = 0
=> h(0) = (4*0 - 1) (2*0 - 3) = -1 * (-3) = +3
et h(x) = 0 ?
il faut que (4x - 1) (-2x - 3) = 0
soit 4x - 1 = 0 => x= 1/4
soit -2x-3 = 0 => x = -3/2
2 solutions
