Đáp án:
Giải thích các bước giải:
a) x² - 7x = 0
⇔ x(x - 7 ) = 0
⇔$\left \{ {{x=0} \atop {x= 7}} \right.$
3) 2x(x + 3) + 5(x+3) = 0
⇔(x+3)(2x+ 5) = 0
⇔ $\left \{ {{x=-3} \atop {x=-5/2}} \right.$
2) 2x² - 6x = 0
⇔ 2x(x - 3) =0
⇔$\left \{ {{x=0} \atop {x=3}} \right.$
4) 3x(x-1)+6(x-1)= 0
⇔(x-1)(3x+6) = 0
⇔$\left \{ {{x=1} \atop {x=-2}} \right.$
5) x(x-4) + (x-4)(3x +1) = 0
⇔ ( x-4)(x + 3x + 1) = 0
⇔ (x-4)(4x+1)=0
⇔$\left \{ {{x = 4} \atop {x=-1/4}} \right.$
6) (x+1)² - 3(x+1) = 0
⇔ (x +1)(x+1-3) = 0
⇔( x+1)(x-2)=0
⇔$\left \{ {{x=-1} \atop {x=2}} \right.$
7) 3x(2x-8) - (2x-8)² = 0
⇔(2x-8)(3x-2x+8)=0
⇔(2x-8)(x+8)=0
⇔$\left \{ {{x=4} \atop {x=-8}} \right.$
8) x(x+2)-3(-x-2) = 0
⇔ x (x+2) +3(x+2) = 0
⇔(x+2)(x+3) = 0
⇔$\left \{ {{x=-2} \atop {x=-3}} \right.$
9) x(1-x)- (x-1) = 0
⇔x(1-x) +(1 -x) = 0
⇔(1-x)(x+1)=0
⇔$\left \{ {{x=1} \atop {x=-1}} \right.$
10) x(2x - 3) - (x-4)(2x-3)=0
⇔(2x-3)(x-x+4)=0
⇔(2x-3)4 = 0
⇔2x-3=0
⇔ x=3/2
