There is no such thing as a "triangular" number (as a number), a triangular number or triangle number counts the objects that can form an equilateral triangle. One object can and Three objects can but not Two objects.
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∙ 9y agoThe formula for the nth triangular number is n(n+1)/2. Therefore, the fourth triangular number is equal to 4 x (4+1) / 2 = (4 x 5) / 2 = 10. The fiftieth triangular number is equal to 50 x (50+1) / 2 = (50 x 51) / 2 = 1275.
The 20th triangular number is 20*21/2 = 210
yes it is!EDIT: No, it is not.
The 81st triangular number is 3321 The nth triangular number is given by tn = n(n+1) ÷ 2 The 81st triangular number is: t81 = 81(81+1) ÷ 2 = 3321
No. ---- The nth triangular number (n must be a whole number > 0) is given by: tn = 1/2 n(n+1) Testing for 49: 1/2 n(n+1) = 49 → n2 + n - 98 = 0 → n = (-1 ± √393)/2 but 393 is not a square number, so n cannot be a whole number which it must be for a triangular number; thus 49 is not a triangular number.
The formula for the nth triangular number is n(n+1)/2. Therefore, the fourth triangular number is equal to 4 x (4+1) / 2 = (4 x 5) / 2 = 10. The fiftieth triangular number is equal to 50 x (50+1) / 2 = (50 x 51) / 2 = 1275.
The nth triangular number is n(n+1)/2
The nth triangular number is n(n+1)/2
The 20th triangular number is 20*21/2 = 210
yes it is!EDIT: No, it is not.
The 81st triangular number is 3321 The nth triangular number is given by tn = n(n+1) ÷ 2 The 81st triangular number is: t81 = 81(81+1) ÷ 2 = 3321
The Nth triangular number is calculated by: N(N + 1) -------- 2 Hope this is useful!
36 is a triangular number. The formula for the nth triangular number is, n(n + 1)/2. So, 36 is the 8th triangular number : 8 x 9/2 = 36
The nth triangular number is n(n+1)/2, so the 2000th triangular number is 2000 * 2001 / 2 = 2,001,000
you need to use this formula: n(n+1) T=--------- 2 So number times (number + 1) divided by 2. If the number you get is the same number as n its a triangular number. if it isn't well it isn't a triangular number.
The nth triangular number is n(n+1)/2
The sum of any two successive triangular number is a square number.The nth triangular number is n(n+1)/2 = (n2 +n)/2The next triangular number is (n+1)*(n+2)/2 = (n2 + 3n + 2)/2Their sum is (2n2 + 4n + 2)/2 = n2 + 2n + 1 = (n + 1)2This is easy to visualise. For example T3 + t4 = 42[T3, the 3th triangular number represented by X,t4, the 4th triangular number represented by x]XXX_____xXX_____xxX_____xxx_____xxxxBring them together and you have:XXXxXXxxXxxxxxxxThe sum of any two successive triangular number is a square number.The nth triangular number is n(n+1)/2 = (n2 +n)/2The next triangular number is (n+1)*(n+2)/2 = (n2 + 3n + 2)/2Their sum is (2n2 + 4n + 2)/2 = n2 + 2n + 1 = (n + 1)2This is easy to visualise. For example T3 + t4 = 42[T3, the 3th triangular number represented by X,t4, the 4th triangular number represented by x]XXX_____xXX_____xxX_____xxx_____xxxxBring them together and you have:XXXxXXxxXxxxxxxxThe sum of any two successive triangular number is a square number.The nth triangular number is n(n+1)/2 = (n2 +n)/2The next triangular number is (n+1)*(n+2)/2 = (n2 + 3n + 2)/2Their sum is (2n2 + 4n + 2)/2 = n2 + 2n + 1 = (n + 1)2This is easy to visualise. For example T3 + t4 = 42[T3, the 3th triangular number represented by X,t4, the 4th triangular number represented by x]XXX_____xXX_____xxX_____xxx_____xxxxBring them together and you have:XXXxXXxxXxxxxxxxThe sum of any two successive triangular number is a square number.The nth triangular number is n(n+1)/2 = (n2 +n)/2The next triangular number is (n+1)*(n+2)/2 = (n2 + 3n + 2)/2Their sum is (2n2 + 4n + 2)/2 = n2 + 2n + 1 = (n + 1)2This is easy to visualise. For example T3 + t4 = 42[T3, the 3th triangular number represented by X,t4, the 4th triangular number represented by x]XXX_____xXX_____xxX_____xxx_____xxxxBring them together and you have:XXXxXXxxXxxxxxxx