问题
解答题
(1)x2+2=3x; (2)(x-1)(x+2)=70; (3)(y+3)2-2=0; (4)(3x-2)2=2(2-x); (5)(x+7)(x-7)=2x-50; (6)(3-2
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答案
(1)移项,得x2+2-3x=0,
即(x-1)(x-2)=0
∴x-1=0或x-2=0
解得x1=1,x2=2.
(2)整理(x-1)(x+2)=70,得
x2+x-72=0,即(x-8)(x+9)=0
∴x-8=0或x+9=0
解得x1=-9,x2=8.
(3)移项,得(y+3)2=2,
∴y+3=±2
解得y=-3±
.2
(4)整理(3x-2)2=2(2-x),得
9x2-10x=0,即x(9x-10)=0
∴x1=0,x2=
.10 9
(5)整理(x+7)(x-7)=2x-50,得
x2-2x+1=0,即(x-1)2=0
∴x-1=0
∴x1=x2=1.
(6)由(3-2
)x2+2(2
-1)x-1=0,得2
[(3-2
)x+1](x-1)=02
∴(3-2
)x+1=0或x-1=02
解得x1=1,x2=-3-2
.2