Question

Find the $20$ $th$ term of the $AP$ whose $7$ $th$ term is $24$ less than the $11$ $th$ term . first term being $12$ .

Answer 1

Given,

$a=12$

$a_7=a_{11}-24$

$a+6d=a+10d-24$

$4d-24=0$

$\therefore d=6$

$a_{20}=a+19d$

$=12+19\times 6$

$=126$