设a-b=3,c-b=1/3,求代数式3(a-c)²+2(c-a)-5的值.
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设a-b=3,c-b=1/3,求代数式3(a-c)²+2(c-a)-5的值.
设a-b=3,c-b=1/3,求代数式3(a-c)²+2(c-a)-5的值.
设a-b=3,c-b=1/3,求代数式3(a-c)²+2(c-a)-5的值.
a-c=3-1/3=8/3
3(a-c)²+2(c-a)-5=64/3-16/3-5=11
a-b=3,c-b=1/3
a-b-(c-b)=a-c=8/3
3(a-c)²+2(c-a)-5
=3(a-c)²-2(a-c)-5
=[3(a-c)-5)][(a-c)-1]
=(3*8/3-5)(8/3-1)
=3*5/3
=5
a-b=3,c-b=1/3两式一减得a-c=8/3 c-a=-8/3代入即可得3(a-c)²+2(c-a)-5=11