分式乘除练习题1.x分之42(x²-y²)乘以35(y-x)分之负的x²

分式乘除练习题
1.x分之42(x²-y²)乘以35(y-x)分之负的x²

x分之42(x²-y²)乘以35(y-x)分之负的x²
-[42(y-x)(x+y)/x]*x^2/35(y-x)
=-6/5 *x(x+y)

将其中一个x约掉,把(x²-y²)看为(x+y)(x-y),与(y-x)约掉并换号,最终结果是5分之(6x²+6xy)