bonjour,
(x-1)/x = 0
x² = 1
x²-1 = 0
(x-1)(x+1) = 0
x =1,-1
x/3 + 2/ (x+4) = 1
x(x+4)+6)/3(x+4) = 1
(x²+4x+6)/3x+12 = 1
x²+4x+6 = 1(3x+12)
x²+4x+6-3x-12 = 0
x²+x-6 = 0
b²-4ac = -1²-4(-6*1) = 1+24 = 25
Δ>0, 2 solutions
(-b-√Δ)/2a = (-1-5)/2 = -6/2 = -3
(-b+√Δ)/2a = (-1+5)/2 = 4/2 = 2