计算：x²-y²/x·-x²/(x-y)²；8y²y³·（-3x/4y²）.

计算：x²-y²/x·-x²/(x-y)²；8y²y³·（-3x/4y²）.
计算：x²-y²/x·-x²/(x-y)²；8y²y³·（-3x/4y²）.

计算：x²-y²/x·-x²/(x-y)²；8y²y³·（-3x/4y²）.
(x²-y²)/x·(-x²)/(x-y)²=(x+y)(x-y) ·(-x)/(x-y)²=-x(x+y)/(x-y)
.
8y²y³·（-3x/4y²）=2y³·（-3x)=-6x·y³