(1) x(x-14)=0
x=0 或x-14=0
∴x=0 或 x=14
(2) x₂+12x+27=0
(x+3)(x+9)=0
∴x=-3或x=-9
(3) x₂=x+56
x²-x-56=0
(x+7)(x-8)=0
x=-7或 x=8
(4) x(5x+4)=5x+4
x(5x+4)-(5x+4)=0
(5x+4)(x-4)=0
x=-4/5 或x=4
(5) 4x₂-45=31x
4x²-31x-45=0
(4x+5)(x-9)=0
x=-5/4或x=9
(6) -3x₂+22x-24=0
3x²-22x+24=0
(3x-4)(x-6)=0
x=4/3或x=6
(7) (x+8)(x+1)=-12
x²+9x+20=0
(x+4)(x+5)=0
x=-4或x=-5
(8) (3x+2)(x+3)=x+14
3x²+10x-8=0
(3x-2)(x+4)=0
x=2/3或x=-4
(9) 2(x+3)₂=x(x+3)
2(x+3)²-x(x+3)=0
(x+3)(x+6)=0
x=-3或x=-6
(10) x₂-2更号5x+2=0
x²-2√5x+5-3=0
(x-√5)²=3
x=√5+√3 x=√5-√3
(11) (x+1)₂-3(x+1)+2=0
[(x+1)-1][(x+1)-2]=0
x(x-1)=0
x=0 或 x=1
楼上第四道错了,正解:
4、x(5x+4)=5x+4
x(5x+4)-(5x+4)=0
(5x+4)(x-1)=0
x=-4/5 或x=1
1、X(X-14)=0
解:因只要X=0,或X-14=0,等式成立,所以:X=0,或X=14
X=14