根号【(a四次方/b四次方)-(a平方/b平方)】-根号【(ab平方+b三次方)/(a-b)】
=√[(a²/b^4)(a²-b²)]-√[b²/(a-b)²]√[(a+b)(a-b)]
=(a/b²)√(a²-b²)-[b/(a-b)]√(a²-b²)
=[a/b²-b/(a-b)]√(a²-b²)
=[(a²-ab-b³)/b²(a-b)]√(a²-b²)
根号【(a四次方/b四次方)-(a平方/b平方)】-根号【(ab平方+b三次方)/(a-b)】
=√[(a²/b^4)(a²-b²)]-√[b²/(a-b)²]√[(a+b)(a-b)]
=(a/b²)√(a²-b²)-[b/(a-b)]√(a²-b²)
=[a/b²-b/(a-b)]√(a²-b²)
=[(a²-ab-b³)/b²(a-b)]√(a²-b²)