bjr
(2x² - 9x + 1)/(2x - 3) - (5x + 1) =
(2x² - 9x + 1)/(2x - 3) - (5x + 1)(2x - 3)/(2x - 3) =
j'étudie le numérateur
2x² - 9x + 1 - (5x + 1)(2x - 3) =
2x² - 9x + 1 - (10x² - 15x + 2x - 3) =
2x² - 9x + 1 - 10x² + 15x - 2x + 3 =
-8x² + 4x + 4 =
4(-2x² + x + 1)
on cherche les racines de -2x² + x + 1
Δ = 1² - 4*(-2)*1 = 9 = 3²
x1 = (-1 - 3)/(-4) = 1 et x2 = (-1 + 3)/(-4) = -1/2
factorisation -2x² + x + 1 = -2(x - 1)(x + 1/2)
= - (x -1)(2x + 1)
numérateur = - 4 (x - 1)(2x + 1)
f(x) - g(x) = -4(x - 1)(2x + 1) / (2x - 3)