（4a²-3b²）-[2(a²-1）+2b²-3]
=4a²-3b²-(2a²-2+2b²-3)
=4a²-3b²-(2a²+2b²-5)
=4a²-3b²-2a²-2b²+5
=(4a²-2a²)+(-3b²-2b²)+5
=2a²-5b²+5