求单项式2xy,6x² y²,-3xy,-4x²y²的和.

问题描述:

求单项式2xy,6x² y²,-3xy,-4x²y²的和.

2xy+6x²y²+(-3xy)+(-4x²y²)
=2xy+6x²y²-3xy-4x²y²
=-xy+2x²y²