Tamil Nadu Board of Secondary EducationSSLC (English Medium) Class 10th

Which term of an A.P. 16, 11, 6, 1, ... is – 54? - Mathematics

Sum

Which term of an A.P. 16, 11, 6, 1, ... is – 54?

Solution

A.P. = 16, 11, 6, 1, ...

It is given that

tn = – 54

a = 16, d = t2 – t1 = 11 – 16 = – 5

∴ tn = a + (n – 1)d

– 54 = 16 + (n – 1)(– 5)

– 54 = 16 – 5n + 5

21 – 5n = – 54

– 5n = – 54 – 21

– 5n = – 75

n = 75/5 = 15

∴ 15th term is – 54.

Is there an error in this question or solution?

APPEARS IN

Samacheer Kalvi Mathematics Class 10 SSLC Tamil Nadu State Board
Chapter 2 Numbers and Sequences
Exercise 2.5 | Q 5 | Page 62