解方程:(1)x 2 -4x+2=0  ...
解方程:(1)x2-4x+2=0(2)(3x-4)2-(x+5)2=0....
解方程:(1)x 2 -4x+2=0 (2)(3x-4) 2 -(x+5) 2 =0.
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(1)x 2 -4x+2=0 ∵a=1,b=-4,c=2,△=4 2 -4×1×2=8, ∴x= = 2± , x 1 =2+ ,x 2 =2- ;
(2)(3x-4) 2 -(x+5) 2 =0, [(3x-4)+(x+5)][(3x-4)-(x+5)]=0, (4x+1)(2x-9)=0, 4x+1=0或2x-9=0, x 1 =- ,x 2 = . |
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