根据杨辉三角,(a+b)^7=
问题描述：
根据杨辉三角,(a+b)^7=
答
(a+b)^7=a^7+7a^6b+21a^5b^2+35a^4b^3+35a^3b^4+21a^2b^5+7ab^6+b^7
根据杨辉三角,(a+b)^7=
(a+b)^7=a^7+7a^6b+21a^5b^2+35a^4b^3+35a^3b^4+21a^2b^5+7ab^6+b^7