要使代数式(2a-b)(2a+b)-(a-2b)²+5mb(b-4/5*a)的值与a有关,与b无关,求m的值?
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要使代数式(2a-b)(2a+b)-(a-2b)²+5mb(b-4/5*a)的值与a有关,与b无关,求m的值?
要使代数式(2a-b)(2a+b)-(a-2b)²+5mb(b-4/5*a)的值与a有关,与b无关,求m的值?
要使代数式(2a-b)(2a+b)-(a-2b)²+5mb(b-4/5*a)的值与a有关,与b无关,求m的值?
原式=4a²-b²-a²-4b²+4ab+5mb²-4mab
=3a²-(5-5m)b²+(4-4m)ab
根据题意
5-5m=0
4-4m=0
所以m=1
化简,原式=4a²-b²-(a²-4ab+4b²)+5mb²-4mab=3a²-5b²+5mb²+4ab-4mba
所以5m=-5,4ma=-4a
所以m=-1
(2a-b)(2a+b)-(a-2b)2+5mb(b-4/5*a)
=4a^2-b^2-a^2+4ab-4b^2+5mb^2-4mab
=(5m-5)b^2+(4a-4ma)b+3a^2
=5(m-1)b^2+4a(1-m)b+3a^2
与b无关,所以b的系数为0,所以m=1