因式分解3x^2-10xy-5y^2=?
问题描述：
因式分解3x^2-10xy-5y^2=?
答
3(X²-10/3XY-5/3Y²)
=3［(X-5/3Y)²-40/9Y²］
=3［X-(5-2√10)/3Y］［X-(5+2√10)/3Y］。
答
3x²-10xy-5y²=3[x²-10xy/3+(5y/3)²]-3×25y²/9-5y²=3(x-5y/3)²-40y²/3=3[(x-5y/3)²-(2√10y/3)²]=3(x-5y/3+2√10y/3)(x-5y/3-2√10y/3)