已知A=x²+2y²-z,B=-4x²+3y²+2z,且A+B+C=0,则多项式C为 ( )A.5x²-y²-zB.x²-y²-zC.3x²-y²-3zD,3x²-5y²-z
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![已知A=x²+2y²-z,B=-4x²+3y²+2z,且A+B+C=0,则多项式C为 ( )A.5x²-y²-zB.x²-y²-zC.3x²-y²-3zD,3x²-5y²-z](/uploads/image/z/987588-36-8.jpg?t=%E5%B7%B2%E7%9F%A5A%3Dx%26%23178%3B%2B2y%26%23178%3B-z%2CB%3D-4x%26%23178%3B%2B3y%26%23178%3B%2B2z%2C%E4%B8%94A%2BB%2BC%3D0%2C%E5%88%99%E5%A4%9A%E9%A1%B9%E5%BC%8FC%E4%B8%BA+%EF%BC%88+%EF%BC%89A.5x%26%23178%3B-y%26%23178%3B-zB.x%26%23178%3B-y%26%23178%3B-zC.3x%26%23178%3B-y%26%23178%3B-3zD%2C3x%26%23178%3B-5y%26%23178%3B-z)
已知A=x²+2y²-z,B=-4x²+3y²+2z,且A+B+C=0,则多项式C为 ( )A.5x²-y²-zB.x²-y²-zC.3x²-y²-3zD,3x²-5y²-z
已知A=x²+2y²-z,B=-4x²+3y²+2z,且A+B+C=0,则多项式C为 ( )
A.5x²-y²-z
B.x²-y²-z
C.3x²-y²-3z
D,3x²-5y²-z
已知A=x²+2y²-z,B=-4x²+3y²+2z,且A+B+C=0,则多项式C为 ( )A.5x²-y²-zB.x²-y²-zC.3x²-y²-3zD,3x²-5y²-z
C=-A-B
=-(x²+2y²-z)-(-4x²+3y²+2z)
=-x²-2y²+z+4x²-3y²-2z
=3x²-5y²-z
选D