解方程,(x-m)的平方等于n(x平方-m平方)(n不等于1)
2个回答
展开全部
(x-m)^2=n(x^2-m^2)
(x-m)^2-n(x^2-m^2)=0
(x-m)^2-n(x-m)(x+m)=0
(x-m)[(x-m)-n(x+m)]=0
(x-m)(x-m-nx-mn)=0
(x-m)[(1-n)x-m(1+n)]=0
x=m或x=m(1+n)/(1-n)
(x-m)^2-n(x^2-m^2)=0
(x-m)^2-n(x-m)(x+m)=0
(x-m)[(x-m)-n(x+m)]=0
(x-m)(x-m-nx-mn)=0
(x-m)[(1-n)x-m(1+n)]=0
x=m或x=m(1+n)/(1-n)
追问
亲,再问一道题:2x的四次方-3x的平方-4等于0,用换元法来解
追答
2x^4-3x^2-4=0
令t=x^2
2t^2-3t-4=0
t^2-3t/2-2=0
t^2-3t/2+9/16-2-9/16=0
(t-3/4)^2-41/16=0
(t-3/4-√41/4)(t-3/4+√41/4)=0
(t=3/4+√41/4或t=3/4-√41/4=0
所以x^2=3/4+√41/4
x^2=3/4+√41/4
x=±√(3+√41)/2
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