已知x+y=5,xy=6,求x(x+y)(x﹣y)﹣x(x+y)2.
解:∵x+y=5,xy=6,
∴原式=x(x+y)(x﹣y)﹣(x+y)=﹣2xy(x+y)=﹣60.
△ABC中,∠C=90°,AB=8,cosA=34,则BC的长____