Đáp án:
Giải thích các bước giải:
a)(2x+5).(x-4)=(x-5).(4-x)
⇔(2x+5).(x-4)-(x-5).(4-x)=0
⇔(2x+5).(x-4)+(x-5).(x-4)=0
⇔(x-4)(2x+5+x-5)=0
⇔(x-4)3x=0
⇔x-4=0 hoặc 3x=0
⇔x=4 hoặc x=0
b)2.(9x^2+6x+1)=(3x+1)(x-2)
⇔2.(3x+1)²=(3x+1)(x-2)
⇔2.(3x+1)²-(3x+1)(x-2)=0
⇔2.(3x+1)(3x+1)-(3x+1)(x-2)=0
⇔(6x+2)(3x+1)-(3x+1)(x-2)=0
⇔(3x+1)(6x+2-x+2)=0
⇔(3x+1)(5x+4)=0
⇔3x+1=0 hoặc 5x+4=0
⇔x= -1/3 hoặc x= -4/5
c)16x^2-8x+1=4(x+3).(4x-1)
⇔(4x-1)²=4(x+3)(4x-1)
⇔(4x-1)(4x-1)=(4x+12)(4x-1)
⇔(4x-1)(4x-1)-(4x+12)(4x-1)=0
⇔(4x-1)(4x-1-4x-12)=0
⇔(4x-1).(-13)=0
⇔4x-1=0
⇔4x=1
⇔x=1/4
