已知A=a²+b²-c²,B=c²-a²+4b²,且A+B+C=0,则C等于( )A.0 B.a²+2b²-c² C.-5b² D.6a²
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![已知A=a²+b²-c²,B=c²-a²+4b²,且A+B+C=0,则C等于( )A.0 B.a²+2b²-c² C.-5b² D.6a²](/uploads/image/z/1596911-23-1.jpg?t=%E5%B7%B2%E7%9F%A5A%3Da%26%23178%3B%2Bb%26%23178%3B-c%26%23178%3B%2CB%3Dc%26%23178%3B-a%26%23178%3B%2B4b%26%23178%3B%2C%E4%B8%94A%2BB%2BC%3D0%2C%E5%88%99C%E7%AD%89%E4%BA%8E%EF%BC%88+%EF%BC%89A.0+B.a%26%23178%3B%2B2b%26%23178%3B-c%26%23178%3B+C.-5b%26%23178%3B+D.6a%26%23178%3B)
已知A=a²+b²-c²,B=c²-a²+4b²,且A+B+C=0,则C等于( )A.0 B.a²+2b²-c² C.-5b² D.6a²
已知A=a²+b²-c²,B=c²-a²+4b²,且A+B+C=0,则C等于( )
A.0 B.a²+2b²-c² C.-5b² D.6a²
已知A=a²+b²-c²,B=c²-a²+4b²,且A+B+C=0,则C等于( )A.0 B.a²+2b²-c² C.-5b² D.6a²
将A、B代人A+B+C=0
得:C=-5b²
∴选择C
C=-(A+B)=-(a²+b²-c²+c²-a²+4b²)=-5b²
选择C