1.（x^2-x)^2+4（3x^2-3x-7)
=（x^2-x)^2+12（x^2-x)^2-28
=(x^2-x+14)(x^2-x-2)
第一个括号内无解,第二个括号内为0
x=2或x=-1
2.y^3+2y^2-5y-10
=y(y^2-5)+2(y^2-5)
=(y+2)(y^2-5)
y=-2 或y=√5或y=-√5
3.x^3-2x^2+1
=x(x^2-2x+1-1)+1
=x(x-1)^2-(x-1)
=(x-1)(x^2-x-1)
x=1或x=(1+√5)/2或x=(1-√5)/2
4.(x^2+3x)/(x^2-5x)=(x^2-5x)/(x^2+3x)
=>x(x+3)^2=x(x-5)^2
=>x[(x+3)^2-(x-5)^2]=0
=>x(2x-6)=0
x=0或x=3
5.2(x^2+1/(x^2))-3(x+1/x)=1
=>2(x^2+1/(x^2)+2-2)-3(x+1/x)=1
=>2(x+1/x)^2-3(x+1/x)-5
=>[2(x+1/x)-5](x+1/x+1)=0
第二个括号内无解
x=1/2或x=2