Question

询问一题数学因式分解的解答题先化解再求值 X（X-1)-(X^2-Y)= -2 求 2份之一（X^2+Y^2)-XY 的

Answer 1

X（X-1)-(X^2-Y)= -2

X^2-X-X^2+Y=-2

Y-X=-2

X-Y=2

(X^2+Y^2)/2-XY

=(X^2-2XY+Y^2)/2

=(X-Y)^2/2

=2^2/2

=2