Question

已知x（x减1）减（x的平方减2y)等于4,求代数式2分之1x的平方减2xy加2y的平方的值?

Answer 1

x(x-1)-(x^2-2y)=4

x^2-x-x^+2y=4

2y-x=4

x^2/2-2xy+2y^2

=(x^2-4xy+4y^2)/2

=(2y-x)^2/2

=4^2/2

=8