Question

the 4th term from the end of A. P-11,-8,-5........49 is
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Answer 1

Solution :-

A.P.=-11,-8,-5......49

a=-11,d=3

tn=a+(n-1)d

49=-11+(n-1)×3

3(n-1)=60

n-1=20

n=21

there are total 21 term

4th term from end is 17th term

t17=-11+10×3

=-11+30

=19

4th term from end is 19.

Answer 2

Step-by-step explanation:

Given AP : -11, -8, -5, .... , 49

first term, a = -11

common difference, d = -8 - (-11) = -8 + 11 = 3

the last term, lets say the nth term, l = 49

nth term, l = a + (n-1)d

=> 49 = -11 + (n-1) × 3

=> 49 = -11 + 3n - 3

=> 49 + 11 + 3 = 3n

=> 3n = 63

=> n = 63/3 = 21

So there are 21 terms in total in the AP

the 4th term from end will be the 18th term from start.

So the 18th term = a + (n-1)d

= -11 + (18-1) × 3

= -11 + 17×3

= -11 + 51

= 40

Hence, the 4th term from the end is 40.