4（x+y)^2+25-20(x+y)怎么解,

4（x+y)^2+25-20(x+y)怎么解,
4（x+y)^2+25-20(x+y)怎么解,

4（x+y)^2+25-20(x+y)怎么解,
4（x+y)^2+25-20(x+y)
=[2(x+y)]²-2×2(x+y)×5+5²
=[2(x+y)-5]²
=(2x+2y-5)²

完全平方公式
原式=[2)x+y)-5]²
=(2x+2y-5)²

4（x+y)^2+25-20(x+y)
=4（x+y)^2-20(x+y)+5²
= [2(x+y)-5]²
= (2x+2y-5)²

4（x+y)^2+25-20(x+y)
=[2(x+y)]²-2×5×2(x+y)+5²
=(2x+2y-5)²