已知:A=3a2-2a+1,B=5a2-3a+2,求2A-3B.
问题描述:
已知:A=3a2-2a+1,B=5a2-3a+2,求2A-3B.
答
2A-3B=2(3a2-2a+1)-3(5a2-3a+2)
=6a2-4a+2-15a2+9a-6
=-9a2+5a-4.