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枫下家园 / 望子成龙 / 征寻数学才子,求解数学难题。不胜感激!
-lilyflower(tiger);
2005-12-29
{680}
(#2685883@0)
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sorry1 7x+1 7x+2 7x+3 7x+300
_____, _____, _____, ........, ________
2 3 4 301
-lilyflower(tiger);
2005-12-29
{326}
(#2685895@0)
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I can solve #2.You should choose 2 from 0,3,6,9, 1 from 1,4,7, and 1 from 2,5,8, so the unswer should be 6*3*3=54.
I can't understand #1
-daceasy(DacEasy);
2005-12-29
{126}
(#2685986@0)
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UpdateThe correct unswer should be 55, as 0,3,6,9 is a possible choice as well.
-daceasy(DacEasy);
2005-12-29
{73}
(#2686020@0)
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Thank you!
-lilyflower(tiger);
2005-12-29
(#2686037@0)
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NOT CORRECT!should plus 3 from {1,4,7} and 1 from {0.3.6.9} that's 1x4=4; and plus 3 from {2,5,8} and 1 from (0,3,6,9} that's another 4; and plus 2 form {1,4,7} and 2 from {2,5,8} that's 3x3=9 and plus 4 from {0,3,6,9} that's 1
TOTAL is 72
-super_eleman(Super Eleman);
2005-12-29
{232}
(#2686036@0)
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I was wrong.It shoud be be 54 + 1 + 4 + 4 which is 60
-daceasy(DacEasy);
2005-12-29
{41}
(#2686043@0)
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wrong again. Should be 63.
-daceasy(DacEasy);
2005-12-29
(#2686050@0)
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Thanks
-lilyflower(tiger);
2005-12-29
(#2686049@0)
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Yes. 72 is correct.
-daceasy(DacEasy);
2005-12-29
(#2686059@0)
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what about (0,3,6,9)?
-goodbaby(小宝);
2005-12-29
(#2686065@0)
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Correct question 1The number of positive integers x with x ≤60 such that each of the rational expressions
(7x+1)/2, (7x+2)/3, (7x+3)/4, .......... (7x+300)/301
is in lowest terms (i.e in each expression, the numerator and denominator have no common factors ) is
(A )1, (B) 2, (C) 3, (D) 4 or (E) 5.
-lilyflower(tiger);
2005-12-29
{291}
(#2686072@0)
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The answer is 344,50,60. it's too complicate for the deduction
-super_eleman(Super Eleman);
2005-12-29
{48}
(#2686171@0)
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Thank you very much. Can you try to explain why?
-lilyflower(tiger);
2005-12-29
(#2686226@0)
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Try to explain it
-super_eleman(Super Eleman);
2005-12-29
{781}
(#2686511@0)
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One more questionIn a convex polygon, exactly five of the interior angles are obtuse. The largest possible number of sides for the polygon is
(A) 7, (B) 8, (C) 9, (D) 10 or (E) 11.
Please give the explanations. Thanks.
-lilyflower(tiger);
2005-12-29
{204}
(#2686232@0)
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Try thissay the side number is N
then the summary is (N-2)*180
5 obtuse, N-5 acute
the maximum is 5*180+(N-5)*90 (a limit which can never be reached)
then (N-2)*180<5*180+(N-5)*90
N<9
the answer is 8
-super_eleman(Super Eleman);
2005-12-29
{197}
(#2686395@0)
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You are a genius! Thank you so much!
-lilyflower(tiger);
2005-12-29
(#2686407@0)
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非常感谢各位的解答,尤其特别致谢数学才子Super Eleman。
-lilyflower(tiger);
2005-12-29
(#2686935@0)