To Find: 20th term of the AP

Given: The series is √2, 3√2, 5√2, 7√2, ….

a1=√2, a2= 3√2 and d= 3√2–√2= 2√2

(Where a=a1 is first term, a2 is second term, an is nth term and d is common difference

of given AP)

Formula Used: an = a + (n – 1)d

a20= a1 + (20 – 1)( 2√2)= √2 + 38√2= 39√2

So 20rd term of AP is equal to 39√2.