先化简再求值3x³-[x³+(6x²-7x)]-2(x³-3x²-4x),其中x=-1
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/27 13:25:09
![先化简再求值3x³-[x³+(6x²-7x)]-2(x³-3x²-4x),其中x=-1](/uploads/image/z/994886-62-6.jpg?t=%E5%85%88%E5%8C%96%E7%AE%80%E5%86%8D%E6%B1%82%E5%80%BC3x%26%23179%3B-%5Bx%26%23179%3B%2B%EF%BC%886x%26%23178%3B-7x%EF%BC%89%5D-2%EF%BC%88x%26%23179%3B-3x%26%23178%3B-4x%29%2C%E5%85%B6%E4%B8%ADx%3D-1)
先化简再求值3x³-[x³+(6x²-7x)]-2(x³-3x²-4x),其中x=-1
先化简再求值3x³-[x³+(6x²-7x)]-2(x³-3x²-4x),其中x=-1
先化简再求值3x³-[x³+(6x²-7x)]-2(x³-3x²-4x),其中x=-1
3x³-[x³+(6x²-7x)]-2(x³-3x²-4x)
=3x³-x³-6x²+7x-2x³+6x²+8x
=15x
因为x=-1 所以原式=-15
3x³-[x³+(6x²-7x)]-2(x³-3x²-4x
=3x³-x³-6x²+7x-2x³+6x²+8x
=15x
x=-1代入得
原式=-15
简单:原式=3x³-x³-6x²+7x-2x³+6x²+8x=9x,∵x=-1,∴9x=9×-1=-9.对吗?