Question

in an A.P if a=-7,d=5 then a18​

Answer 1

$a = - 7 \: \: \: \: \: \: \: \: \: \: \: \: d = 5 \: \: \: \: \: \: \: \: \: \: n = 18$

using formula

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

$a18 = - 7 + 17 \times 5$

$a18 = 85 - 7$

$a18 = 78$

Answer 2

Answer:

a₁₈  = 78

Step-by-step explanation:

Given problem

In an A.P  if first term a = - 7 and

common difference  d = 5  then  a₁₈ = ?  

here we need to find a₁₈  

we know that in an AP nth term  $T_{n}$ = a + (n-1) d

⇒  18th term in given AP ,    T₁₈ =  (-7) + (18 -1) 5

                                                   = -7 + (17)5

                                                   = -7 + 85

                                                   = 78

⇒ a₁₈  = 78