Question

The 11th term and the 21st term of an A.P are 16 and
39 respectively. then find the 45th term of that AP​

Answer 1

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• The 11th term and the 21st term of an A.P are 16 and
• 39 respectively. then find the 45th term of that AP

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Given :

11st term = 16 (1)

21st term = 39 (2)

From I and ii equation

a+10d= 16 (3)

a+20d=39 (4)

From 3 and 4 equation

10d= 23

D = 2.3

Putting value of D in equation 3

a+10(23/10)=16

a+23=16

a= -7

So, 45th term is

= a+(n-1)d

= -7+(45-1)2.3

= 94.2