a) x² + 3x = 0 => x(x+3) = 0 => x = 0 ou x = -3
b) 2t² - 3t - 4 - t²+ 4t + 6 = 0 => t² + t + 2 = 0
Δ = 1 - 8 = -7 => pas de racine
c) t² + 4t + 4 - 2t² - 5t + 2 = 0 => -t² - t + 6 = 0 => t = 3 ou t = -2
d) x² + 3x + 2 - x² - 7x - 12 - x² -11x - 30 = 0
=> -x² -15x - 40 = 0
=> Δ = 225 - 160 = 65 => x1 = (15 - √65)/-2 ou x2 = (15 + √65)/-2
bonne journée