Question

计算(1/2x-y-1)的平方

要有过程

Answer 1

解：
这里给出三项平方公式：
(a+b+c)²
=(a+b+c)(a+b+c)
=a²+ab+ac+ab+b²+bc+ac+bc+c²
=a²+b²+c²+2ab+2bc+2ac

因此：
[(1/2)x-y-1]²
=[(1/2)x-y-1][(1/2)x-y-1]
=(1/4)x²-(1/2)xy-(1/2)x-(1/2)xy+y²+y-(1/2)x+y+1
=(1/4)x²+y²+1-xy-x+2y

另：根据公式可直接口算出来，加快计算！

Answer 2

(1/2x-y-1)²
=(x/2-y-1)*x/2-(x/2-y-1)*y-(x/2-y-1)*1
=x²/4-xy/2-x/2-xy/2+y²+y-x/2+y+1
=x²/4+y²+1-xy-x+2y

Answer 3

(1/2x-y-1)²
=[(x/2-y)-1]²
=(x/2-y)²-2(x/2-y)+(-1)²
=(x/2)²-2*(x/2)*y+(-y)²-x+2y+1
=x²/4-xy+y²-x+2y+1

Answer 4

接
(a+b+c)²
=(a+b+c)(a+b+c)
=a²+ab+ac+ab+b²+bc+ac+bc+c²
=a²+b²+c²+2ab+2bc+2ac

[(1/2)x-y-1]²
=[(1/2)x-y-1][(1/2)x-y-1]
=(1/4)x²-(1/2)xy-(1/2)x-(1/2)xy+y²+y-(1/2)x+y+1
=(1/4)x²+y²+1-xy-x+2y