已知A=8x^2y-6xy^2-3xy,B=7xy^2-2xy+5x^2y求A-B
问题描述：
已知A=8x^2y-6xy^2-3xy,B=7xy^2-2xy+5x^2y求A-B
答
=(8x²y-6xy²-3xy)-(7xy²-2xy+5x²y)
=8x²y-6xy²-3xy-7xy²+2xy-5x²y
=(8x²y-5x²y)+(-6xy²-7xy²)+(-3xy+2xy)
=3x²y-13xy²-xy