若有理数a,b满足丨3a+1丨+(2b-1)^2=0,求式子3a^2 - 2b^2/ab的值

问题描述:

若有理数a,b满足丨3a+1丨+(2b-1)^2=0,求式子3a^2 - 2b^2/ab的值

a=-1/3, b=1/2
带入式子中,求解

3a+1=0
2b-1=0
a=-1/3
b=1/2

3a^2-2b^2/ab
=3*1/9-2*1/4÷1/6
=1/3-3
=-8/3

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丨3a+1丨+(2b-1)^2=0
则 3a+1=0 a=-1/3
2b-1=0 b=1/2
所以(3a^2 - 2b^2)/ab
=(3×1/9-2×1/4)/(-1/3)×1/2
=(-1/6)/(-1/6)
=1