x³-2x²=?a²-9b²=?5x²y-20y³=?3a³b²-6a²b+3a=?

问题描述:

x³-2x²=?a²-9b²=?5x²y-20y³=?3a³b²-6a²b+3a=?

x³-2x²=x²*(x-2)
a²-9b²=a²-(3b)²=(a-3b)(a+3b)
5x²y-20y³=5y(x²-4y²)=5y[x²-(2y)²]=5y(x-2y)(x+2y)
3a³b²-6a²b+3a=3a(a²b²-2ab+1)=3a(ab-1)²