Given x + y = 3, xy = - 10, find (1) x ^ 2-xy = y ^ 2; (2) X-Y | Math enthusiast | Mathematical art

Given x + y = 3, xy = - 10, find (1) x ^ 2-xy = y ^ 2; (2) X-Y

1、
(x+y)^2=3^2
x^2+2xy+y^2=9
Subtract 3xy = - 30 from both sides
x^2-xy+y^2=9+30=39
2、
(x-y)^2
=x^2-2xy+y^2
=(x^2-xy+y^2)-xy
=39+10
=49
So | X-Y | = 7

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