Răspuns:
1) 12x²-5x=0
x(12x-5)=0
x 1 =0
Sau
12x-5=0
12x=5
x 2= 5/12
2) 6x²+11x-7=0
6x²+14x-3x-7=0
2x(3x+7)-3x-7=0
2x(3x-7)-(3x+7)=0
(3x+7)(2x-1)=0
3x+7=0
3x=-7
x 1 = - 7/3
2x-1=0
2x=1
x 2 =1/2
3) x²-20x+84=0
x²-6x-14x+84=0
x(x-6)-14x+84=0
x(x-6)-14(x-6)=0
(x-6)(x-14)=0
x-6=0
x 1 =6
x-14=0
x 2 =14
Explicație pas cu pas: