Re: [計量] CAT計量問題請教(II) 補遺

看板GRE (GRE入學考試)作者leeneil (Paradise)時間16年前 (2009/08/05 23:21)推噓1(1推 0噓 0→)

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補遺 ※ 引述《leeneil (Paradise)》之銘言： : CAT19 : 17. : the first term of a sequence is 1, and each of the following terms is less than than 3 times preceding : term. : COL A the smaller number that is greater than 100 in the sequence : COL B 120 : ans A 題目沒問題嗎? 不懂@@ : 26. : An obtuse triangle has sides of lengths of 11, 15, and k, where k is an integer. : COL A the number of K values of K : COL B 13 : ans C 鈍角三角形的想法是，最長的邊(斜邊)平方大於另外兩股平方和 11 -> 121 15 -> 225 假設K為長邊，則有19,20,21,22,23,24,25可行 (K^2 > 121 + 225 = 346，但是受 K < 11+15限制) 假設15為長邊，則K可以是10,9,8,7,6,5 (225 > K^2 + 121，但是受 K + 11 > 15限制) 故有13種可能 : 28. the two-digit integers N ans N' are positive and have the same digits, but in reversed ordered. how many : integers N are there if the sum of N and N' is a percect square?? : ans 8 寫成式子，假設兩個digits分別是x和y N = 10x + y 且 N' = 10y + x 又知 N + N' = 11x + 11 y = 11(x+y) 為一完全平方數那麼就考慮x+y=11的組合即可 2:9 3:8 4:7 5:6 6:5 7:4 8:3 9:2 故答案為8 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 221.169.5.190 ※ 編輯: leeneil 來自: 221.169.5.190 (08/05 23:24)