41. n是某个数的三次方减1,且是4个连续整数之和,问n
(1) 100<n<1000
(2) n<400
求救NN这题怎么算的呢
举报
n = x^3 - 1
n = a + (a+1) + (a+2) + (a+3)
x^3 - 1 = a + (a+1) + (a+2) + (a+3)
x^3 = 4a + 7
1) 100<n<1000, 7^3 works
2) n<400, 7^3 and 4^3 - no good
Answer is A.
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