Question

根号（2x^2-5x+4)+根号(x^2-5x+5)=?

Answer 1

[v(2x^2-5x+4)-v(x^2-5x+5)]*[v(2x^2-5x+4)+v(x^2-5x+5)]

=(2x^2-5x+4)-(x^2-5x+5)

=x^2-1

=(x-1)(x+1),

——》[v(2x^2-5x+4)+v(x^2-5x+5)]=x+1,

——》v(x^2-5x+5)=1,

——》x^2-5x+4=0=(x-1)(x-4),

——》x=1,或x=4.