用两种方法计算[(2x/(x-3)-x/(x+3)]乘以(x^2-9)/x
问题描述：
用两种方法计算[(2x/(x-3)-x/(x+3)]乘以(x^2-9)/x
答
[(2x/(x-3)-x/(x+3)]乘以(x²-9)/x
=[2x(x+3)-x(x-3)]/(x-3)(x+3)乘以(x-3)(x+3)/x
=(x²+9x)/x
=x+9
[(2x/(x-3)-x/(x+3)]乘以(x²-9)/x
=[2x/(x-3)乘以(x²-9)/x]-[x/(x+3)乘以(x²-9)/x]
=2(x+3)-(x-3)
=2x+6-x+3
=x+9