作业帮帮我解决这4道数学题吧.第1.2.4.5题.
来源：学生作业帮 编辑：拍题作业网作业帮 分类：数学作业 时间：2024/04/28 14:02:33
帮我解决这4道数学题吧.第1.2.4.5题.
(1)(2x+1)(x+3)=2x²+x+6x+3=2x²+7x+3
(2)(m+2n)(3n-m)=3mn+6n²-m²-2mn=6n²+mn-m²
(3)(a-1)²=a²-2a+1
(4)(a+3b)(a-3b)=a²-9b²
(5)(2x²-1)(x-4)=2x³-8x²-x+4
(6)(x²+2x+3)(2x-5)=2x³+4x²+6x-5x²-10x-15=2x³-x²-4x-15
(1)(x+2)(x+3)=x²+2x+3x+6=x²+5x+6
(2)(x-4)(x+1)=x²-4x+x-4=x²-3x-4
(3)(y+4)(y-2)=y²+4y-2y-8=y²+2y-8
(4)(y-5)(y-3)=y²-5y-3y+15=y²-8y+15
4. (1)(4a-b²)(-2b)=2b³-8ab
(2)2x²(x-1/2)=2x³-x²
(3)5ab(2a-b+0.2)=10a²b-5ab²+ab
(4)(2a²-2/3a-4/9)(-9a)=-18a³+6a²+4a
5 (1)(x-6)(x-3)=x²-6x-3x+18=x²-9x+18
(2)(x+1/2)(x-1/3)=x²+1/2x-1/3x-1/6=x²+1/6x-1/6
(3)(3x+2)(x+2)=3x²+2x+6x+4=3x²+8x+4
(4)(4y-1)(5-y)=20y-5-4y²+y=-4y²+21y-5
(5)(x-2)(x²+4)=x³-2x²+4x-8
(6)(x-y)(x²+xy+y²)=x³-x²y+x²y-xy²+xy²-y³=x³-y³
(2)(m+2n)(3n-m)=3mn+6n²-m²-2mn=6n²+mn-m²
(3)(a-1)²=a²-2a+1
(4)(a+3b)(a-3b)=a²-9b²
(5)(2x²-1)(x-4)=2x³-8x²-x+4
(6)(x²+2x+3)(2x-5)=2x³+4x²+6x-5x²-10x-15=2x³-x²-4x-15
(1)(x+2)(x+3)=x²+2x+3x+6=x²+5x+6
(2)(x-4)(x+1)=x²-4x+x-4=x²-3x-4
(3)(y+4)(y-2)=y²+4y-2y-8=y²+2y-8
(4)(y-5)(y-3)=y²-5y-3y+15=y²-8y+15
4. (1)(4a-b²)(-2b)=2b³-8ab
(2)2x²(x-1/2)=2x³-x²
(3)5ab(2a-b+0.2)=10a²b-5ab²+ab
(4)(2a²-2/3a-4/9)(-9a)=-18a³+6a²+4a
5 (1)(x-6)(x-3)=x²-6x-3x+18=x²-9x+18
(2)(x+1/2)(x-1/3)=x²+1/2x-1/3x-1/6=x²+1/6x-1/6
(3)(3x+2)(x+2)=3x²+2x+6x+4=3x²+8x+4
(4)(4y-1)(5-y)=20y-5-4y²+y=-4y²+21y-5
(5)(x-2)(x²+4)=x³-2x²+4x-8
(6)(x-y)(x²+xy+y²)=x³-x²y+x²y-xy²+xy²-y³=x³-y³