已知A=x2-2x+1,B=2x2-6x+3.求:(1)A+2B.(2)2A-B.
问题描述:
已知A=x2-2x+1,B=2x2-6x+3.求:(1)A+2B.(2)2A-B.
答
(1)由题意得:A+2B=x2-2x+1+2(2x2-6x+3),
=x2-2x+1+4x2-12x+6,
=5x2-14x+7.
(2)2A-B=2(x2-2x+1)-(2x2-6x+3),
=2x2-4x+2-2x2+6x-3,
=2x-1.