Question

find the sum of first 15th term of AP IS 2,8,11,14​

Answer 1

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$\huge\bold\red{Answer}$

Given,

• First term(a) = 2
• Common difference(d) = 8-2 = 6
• n = 15.

To Find,

• Sum of 15th terms = ?

Solution:

Sum of first 15 term =n/2 [2a + (n-1) × d]

=15/2[2×2+(14)×3]

=15/2 × 46

=15 × 23

=345

●Hence, the 15th term of AP is 345.●

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I Hope It Helps You✌️

Answer 2

${\huge{\bold{\purple{\bigstar{\boxed{\boxed{\bf{Question}}}}}}}}$

find the sum of first 15th term of AP is 2,8,11,14

${\huge{\bold{\purple{\bigstar{\boxed{\boxed{\bf{Answer}}}}}}}}$

${\bold{\blue{\boxed{\bf{Given}}}}}$

• first term = a = 2
• common diff. = d = 6
• no. of times = n = 15

${\bold{\blue{\boxed{\bf{To\:find}}}}}$

sum of first 15 terms

${\bold{\blue{\boxed{\bf{Formulae\:used}}}}}$

$\dfrac{n}{2}[2a+(n-1)\times d]$

${\bold{\blue{\boxed{\bf{Solution}}}}}$

$\dfrac{n}{2}[2a+(n-1)\times d]$

$\dfrac{15}{2}[2*2+(15-1)\times 6]$

$7.5[4 + 14 * 6]$

$7.5[4 + 84]$

$7.5 * 88$

$660$

${\bold{\blue{\boxed{\boxed{\bf{sum\:of \: first\:15 terms = 660}}}}}}$

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