(2a²-3ab+b²)/(a²-b²)
=(2a-b)(a-b)/(a+b)(a-b)
=(2a-b)/(a+b)
∵3a=4b
∴a=4b/3
∴原式=(2a-b)/(a+b)
=(8b/3-b)/(4b/3+b)
=(8-3)/(4+3)
=5/7
(2a²-3ab+b²)/(a²-b²)
=(2a-b)(a-b)/(a+b)(a-b)
=(2a-b)/(a+b)
∵3a=4b
∴a=4b/3
∴原式=(2a-b)/(a+b)
=(8b/3-b)/(4b/3+b)
=(8-3)/(4+3)
=5/7