B: 3(3x+5)(-5x+1) = 0
= 3(-15x²+3x-25x+5) = -45x²+9x-75x+15 = -45x²-66x+15
delta = 7056
x1 = 0,2
x2 = -1,666
C: (4x-7)(2x+3) = 3(4x-7)(5x+11)
(4x-7)(2x+3)-3(4x-7)(5x+11) = 0
(4x-7) ((2x+3)-3(5x+11)) = 0
(4x-7) (2x+3-15x-33) = 0
8x²+12x-60x²-132-14x-21+105x+ 231 = 0
-52x²+103x+78 = 0
delta=26833
x1 = 2,565
x2 = -0,585
D: (x-4)² = 5
(x-4)²-5 = 0
x²-8x+16-5=0
x²-8x+11=0
delta=b²-4ac=20
x1 = (-b+racine(delta))/2a = (8+racine(20))/2 = 4+racine(20)/2
= 4+racine(4*5)/2 = 4+racine(4)*racine(5)/2 = 4+2 racine(5)/2 = 4+racine(5) = 6,236...
x2 = (-b-racine(delta))/2a = (8-racine(20))/2 = 4-racine(20)/2
= 4-racine(4*5)/2 = 4-racine(4)*racine(5)/2 = 4-2 racine(5)/2 = 4-racine(5) = 1,764...
