Question

find
the 18th term of the AP
2,5, 8
11,.........​

Answer 1

Given :

• A.P. = 2,5, 8, 11,...

To find :

• 18th term

Formula used :

• Tn = a+(n-1)d

where :-

• a = first term
• n = number of terms
• d = common difference
• Tn = nth term

Solution :

From the given AP we know that :-

first term = 2

⟹common difference = second term - first term

⟹common difference = 5 - 2

⟹common difference = 3

To find 18th term we will use the following formula :-

⟹ Tn = a+(n-1)d

Now put :-

• a = 2
• n = 18
• d = 3
• Tn = T18

⟹ Tn = a+(n-1)d

⟹ T18 = 2+(18-1)3

⟹ T18 = 2+51

⟹ T18 = 53

Answer :

Therefore , 18th term of given A.P = 53

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Learn more :

1. Tn = a+(n-1)d

2. Sn = n/2[2a+(n-1)d]

3. Sn = n/2(a+l)

where :-

• a = first term
• n = number of terms
• d = common difference
• Tn = nth term

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