Question
Find:
$10^{th}$ term of the $A.P. -40, -15, 10, 35, .....$
$10^{th}$ term of the $A.P. -40, -15, 10, 35, .....$
✓
Answer
Given $A.P.$ is
$-40, -15, 10, 35, .....$
First term $(a) = -40$
Common difference $(d) =$ second term $-$ first term
$= -15 - (-40)$
$= 40 - 15$
$= 25$
$\mathrm{n}^{\text {th }}$ term of an A.P. $a_n=a+(n-1) d$
$10^{\text {th }}$ term of A.P. $a_{10}=-40+(10-1) 25$
$= -40 + 9 × 25$
$= -40 + 225$
$= 185$
$-40, -15, 10, 35, .....$
First term $(a) = -40$
Common difference $(d) =$ second term $-$ first term
$= -15 - (-40)$
$= 40 - 15$
$= 25$
$\mathrm{n}^{\text {th }}$ term of an A.P. $a_n=a+(n-1) d$
$10^{\text {th }}$ term of A.P. $a_{10}=-40+(10-1) 25$
$= -40 + 9 × 25$
$= -40 + 225$
$= 185$
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