(12-x-y)² 化简

(12-x-y)² 化简
(12-x-y)² 化简

(12-x-y)² 化简
原式=[12-(x+y)]²
=144-24(x+y)+(x+y)²
=144-24x-24y+x²+2xy+y²

144-24x-24y+x^2+2xy+y^2

原式=[12-（x+y）]^2
=12^2-2*12(x+y)+(x+y)^2
=……后面你知道了吧...