如果A+3x²-xy+y²,B=2x²-3xy-2y²,那么2A-3B等于多少?真着急!
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如果A+3x²-xy+y²,B=2x²-3xy-2y²,那么2A-3B等于多少?真着急!
如果A+3x²-xy+y²,B=2x²-3xy-2y²,那么2A-3B等于多少?真着急!
如果A+3x²-xy+y²,B=2x²-3xy-2y²,那么2A-3B等于多少?真着急!
2A-3B
=2(3x²-xy+y²)-3(2x²-3xy-2y²)
=6x²-2xy+2y²-6x²+9xy+6y²
=7xy+8y²
2A=6x²-2xy+2y²
3B=6x²-9xy-6y²
2A-3B=7xy+8y²