5) Find the 17th term of the A.P 4 , 9 , 14 ,…………

Solution:

First term = 4

              a = 4

Common difference = 9 - 4  

                                 d = 5

n = 17

General term of an A.P

tn =  a + (n - 1) d

tn =  4 + (17 - 1) (5)

    = 4 + 16 (5)

    = 4 + 80

    = 84

Therefore 17th of A.P is 84

(4) Find the 12th term of the A.P √2 , 3 √2 , 5 √2 , …………

Solution :

First term (a)  = √2

Common difference (d)  = 3 √2 - √2 = 2 √2

n = 12

General term of an A.P

tn =  a + (n - 1) d

t₁₂ =  √2 + (12 - 1) (2√2)

=  √2 + 11 (2√2)

=  √2 + 22 √2

=  23 √2

Hence, 12th of A.P is 23 √2