计算(x+4)·(-2x)-(x+1)(x-1)+(-3x+2)(x+1)；（3x-y)(y+3x)-(4x-3x)(4x+3y_数学解答

计算(x+4)·(-2x)-(x+1)(x-1)+(-3x+2)(x+1)；（3x-y)(y+3x)-(4x-3x)(4x+3y)
(a+b)(a-b)+a(2b-a),其中a=1.5,b=-2
过程要全一点,还有,第十五章整式的乘除与因式分解第三课时多项式乘以多项式的答案麻烦发一下,

人气：454 ℃　时间：2020-03-25 05:29:12

解答

(x+4)·(-2x)-(x+1)(x-1)+(-3x+2)(x+1)
=-2x²-8x-(x²-1)+(-3x²-x+2)
=-2x²-8x-x²+1-3x²-x+2
=-2x²-x²-3x²-8x-x+2+1
=-6x²-9x+3
（3x-y)(y+3x)-(4x-3y)(4x+3y)
=（3x-y)(3x+y)-(4x-3y)(4x+3y)
=9x²-y²-(16x²-9y²)
=9x²-y²-16x²+9y²
=9x²-16x²+9y²-y²
=-7x²+8y²
(a+b)(a-b)+a(2b-a)
=a²-b²+2ab-a²
=a²-a²+2ab-b²
=2ab-b²
=b(2a-b)
=-2*[2*1.5-(-2)]
=-2*(3+2)
=-2*5
=-10