Question

an AP d= -4 n= 7 a (n)=4 then a is​

Answer 1

Question :–

▪︎ In An A.P. d = -4 , n = 7 and $\: \rm ( a_{n} ) = 4 \:$ then find a .

ANSWER :–

$\\ \longrightarrow \: \: \large { \green{ \boxed { \rm{a = 28 } }}}\:$

EXPLANATION :–

GIVEN :–

• Common difference (d) = -4

• Total number of terms (n) = 7

• nth term $\: \rm ( a_{n} ) = 4 \:$

TO FIND :–

• First term (a) = ?

SOLUTION :–

• We know that nth term of A.P. is –

$\\ \: \: \bigstar \: \: \: \: { \red{ \boxed { \rm{( a_{n} )=a + (n - 1)d} }}}\:$

• Now put the values –

$\\ \implies { \rm{a_{n} =a + (n - 1)d} }\:$

$\\ \implies { \rm{4=a + (7 - 1)( - 4)} }\:$

$\\ \implies { \rm{4=a + (6)( - 4)} }\:$

$\\ \implies { \rm{4=a - 24} }\:$

$\\ \implies { \rm{4 + 24=a } }\:$

$\\ \implies \large { \green{ \boxed { \rm{a = 28 } }}}\:$

Hence , First term (a) = 28