Question

已知A=2X-3,B=-3X+5，B=-3X+5，计算

1. 3A(-2B)
2. (5A+B)(2A-3B)

Answer 1

1. 3A(-2B)
=3(2X-3)[-2(-3X+5)]
=-6(-6X²+X-15)
=36X²-6X+90

2. (5A+B)(2A-3B)
=[5(2X-3)-3X+5][2(2X-3)-3(-3X+5)]
=(10X-15-3X+5)(4X-6+9X-15)
=(7X-10)(13X-21)
=91X²-120X-147X+210
=91X²-267X+210

追问

第2题应该是=91X²-277X+210

追答

是的
2. (5A+B)(2A-3B)
=[5(2X-3)-3X+5][2(2X-3)-3(-3X+5)]
=(10X-15-3X+5)(4X-6+9X-15)
=(7X-10)(13X-21)
=91X²-130X-147X+210
=91X²-277X+210