Question

先化简,再求值.x(X-1)-(x的平方-y)=-6,求二分之(x的平方+y的平方）-xy的值

先化简,再求值.x(X-1)-(x的平方-y)=-6,求二分之(x的平方+y的平方-xy的值
速求！！！！！！！！！！！！！！要过程！！！详解！！！！！！！！

Answer 1

x(x - 1) - (x² - y) = x² - x - x² + y = y - x = -6
(x² + y²)/2 - xy
= (x² - 2xy + y²)/2
= (y - x)²/2
= (-6)²2
= 18

Answer 2

先化简,再求值.x(X-1)-(x的平方-y)=-6,求二分之(x的平方+y的平方-xy的值

x(X-1)-(x^2-y)=-6,
x^2-x-x^2+y=-6
x-y=6

(x^2+y^2)/2-xy
=(x^2+y^2-2xy)/2
=(x-y)^2/2
=6^2/2
=36/2
=18

Answer 3

由已知得x-y=6
所求化简为（x-y）∧2/2
答案为18