Bonjour ,
1)
g(x) = 4x² - 9 = (2x)² - (3)² = (2x-3)(2x+3)
2)
g(x) = 0
4x² - 9 = 0
(2x-3)(2x+3)=0
2x-3 = 0 ou 2x+3 = 0
x = 3/2 ou x = -3/2
3)
x. | - ∞ -3/2. 3/2. + ∞
2x-3. | - -. 0. +
2x + 3. | -. 0. + +
(2x-3)(2x+3) | + 0 - 0 +
