Question

1.
If 7th term of an AP is 26 find the sum of 5th and 9th term is
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Answer 1

$\underline{\textbf{Given:}}$

$\textsf{7 th term of an A.P is 26}$

$\underline{\textbf{To find:}}$

$\textsf{The sum of 5 th and 9 th terms}$

$\underline{\textbf{Solution:}}$

$\underline{\textbf{Concept used:}}$

$\textsf{The n th term of A.P a, a+d, a+2d, . . . . . . is}$

$\boxed{\mathsf{t_n=a+(n-1)d}}$

$\mathsf{Here,\;t_7=26}$

$\implies\mathsf{a+6d=26}$

$\mathsf{Now,}$

$\mathsf{t_5+t_9}$

$\mathsf{=(a+4\,d)+(a+8\,d)}$

$\mathsf{=2a+12\,d}$

$\mathsf{=2(a+6\,d)}$

$\mathsf{=2(26)}$

$\mathsf{=52}$

$\therefore\textbf{Sum of the 5 th and 9 th term is 52}$

$\underline{\textbf{Find more:}}$

If for an a.p.s 15= 147 and s 14 = 123 find t 15

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