先化简,在求值 5a²+3b²+2(a²-b²)-(5a²-3b²),其中a=-1,b=1/2

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先化简,在求值 5a²+3b²+2(a²-b²)-(5a²-3b²),其中a=-1,b=1/2

5a²+3b²+2(a²-b²)-(5a²-3b²)
=5a²+3b²+2a²-2b²-5a²+3b²
=2a²+4b²
=2×1+4×1/4
=2+1
=3