Question

2. Which of the following are terms of the series with nth term T-3n +17? a) 80 b) 170 c)217 d) 312 e) 278 f) 3566

Answer 1

Answer:

The correct options are a,b,e and f.

Step-by-step explanation:

It is given that the nth terms of the series is defined as

$T_n=3n+17$

Subtract 17 from both the sides.

$T_n-17=3n$

Divide both sides by 3.

$\frac{T_n-17}{3}=n$

The term Tₙ is a term of given series if n is a positive integer.

(a) The given term is 80.

$n=\frac{80-17}{3}=21$

Since n is a positive integer, therefore 80 is a term of given series.

(b) The given term is 170.

$n=\frac{170-17}{3}=51$

Since n is a positive integer, therefore 170 is a term of given series.

(c) The given term is 217.

$n=\frac{217-17}{3}=66.67$

Since n is not a positive integer, therefore 217 is a term of given series.

(d) The given term is 312.

$n=\frac{312-17}{3}=98.33$

Since n is not a positive integer, therefore 312 is a term of given series.

(e) The given term is 278.

$n=\frac{278-17}{3}=87$

Since n is a positive integer, therefore 278 is a term of given series.

(f) The given term is 3566.

$n=\frac{3566-17}{3}=1183$

Since n is a positive integer, therefore 3566 is a term of given series.

Thus, the correct options are a, b, e and f.