chelsy
幼苗
共回答了23个问题采纳率:91.3% 举报
(1)(5-8x)^2=2
(8x-5)^2-2=0
(8x-5-√2)(8x-5+√2)=0
x=(5+√2)/8或x=(5-√2)/8
(2)x^2+8x=20
x^2+8x-20=0
(x+10)(x-2)=0
x=-10或x=2
(3)3x^2+2x-3=0
x^2+2x/3-1=0
x^2+2x/3+1/9-1/9-1=0
(x+1/3)^2-10/9=0
(x+1/3-√10/3)(x+1/3+√10/3)9=0
x=-1/3+√10/3或x=-1/3-√10/3
(4)(x-1)(x+2)=70
x^2+x-2=70
x^2+x-72=0
(x+9)(x-8)=0
x=-9或x=8
1年前
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