Question

if 11th term of AP is 38 and 16th term is 73 find 20th term​

Answer 1

Answer:

11th term of AP is 38 and 16th term is 73 find 20th term

Answer 2

solution - let a be the first term and d be the common difference of the given AP.

T11 = 38= a+10d=38 ........... equation i

T16= 73= a+15d=73............. equation ii

on subtracting i from ii we get

5d= 45

d= 9

putting d=9 in equation i we get

a+10×9=38

a+90=38

a= -52.

thus, a=-52 and d=9.

T20= a+(n-1)d

= -52+(20-1)×9

=. -52+19×9

=. -52+171

=. 119

hence the 20th term of the AP is 119