Question

先化简,后求值(x^2y-4^3^/x^2+4xy+4y^2)·(4xy/x-2y+x),其中x=根号2-1,y=根号2

Answer 1

(x^2y-4^y3^/x^2+4xy+4y^2)·(4xy/x-2y+x),其中x=根号2-1,y=根号2+1

=(x²y-4y³)/(x+2y)²*(4xy+x²-2xy)/(x-2y)

=y(x+2y)(x-2y)/(x+2y)²*x(x+2y)/(x-2y)

=xy

=(√2-1)(√2+1)

=2-1

=1