16(a+2b)-9(a-2b)平方
3a(a+b)平方-27ab平方
1/7(x-y)立方+7(y-x)
16(a+2b)-9(a-2b)平方
3a(a+b)平方-27ab平方
1/7(x-y)立方+7(y-x)
{4(a+2b)+3(a-2b)}{4(a+2b)-3(a-2b)}
=(7a+2b)(a+14b)
3a(a+b)平方-27ab平方
=3a{(a+b)^2-9b^2)
=3a(a+b-3b)(a+b+3b)
=3a(a-2b)(a+4b)
1/7(x-y)立方+7(y-x)
=1/7(x-y){(x-y)^2-47}
=1/7(x-y)(x-y+7)(x-y-7)