作业帮若x=-2,求3x²-[7x²-2（x²-3x）-2x]的值.老师让的没办法啊
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/14 05:17:20
![若x=-2,求3x²-[7x²-2（x²-3x）-2x]的值.老师让的没办法啊](/uploads/image/z/312467-59-7.jpg?t=%E8%8B%A5x%3D-2%2C%E6%B1%823x%26%23178%3B-%5B7x%26%23178%3B-2%EF%BC%88x%26%23178%3B-3x%EF%BC%89-2x%5D%E7%9A%84%E5%80%BC.%E8%80%81%E5%B8%88%E8%AE%A9%E7%9A%84%E6%B2%A1%E5%8A%9E%E6%B3%95%E5%95%8A)
若x=-2,求3x²-[7x²-2（x²-3x）-2x]的值.老师让的没办法啊
若x=-2,求3x²-[7x²-2（x²-3x）-2x]的值.
老师让的没办法啊
若x=-2,求3x²-[7x²-2（x²-3x）-2x]的值.老师让的没办法啊
原式=3x²-(7x²-2x²+6x-2x)
=3x²-(5x²+4x)
=3x²-5x²-4x
=-2x²-4x
=-2×4-4×(-2)
=-8+8
=0