Question

Find the $12th$ term from the end in $A.P.13,18,23,.158$.

Answer 1

AP - 13, 18,23 _ _ _ _ _ 158

$a=13d=5a_n=158$

$a_n=a+(n-1)d$

$158=13+(n-1)d$

$n-1=\frac{145}{5}=29$

n = 30

${11}^{th}$ term from end$=(n-\mu +1{)}^{th}$

term from start

${12}^{th}$ term from end

$={19}^{th}$ term from start

$a_{19}=a+18d$

$=13+18\left(5\right)$

$=13+90$

$a_{19}=103$