Question

Find the 15th term from the last term of an A.P. 6, 12, 18, …… 600.​

Answer 1

Answer:

The 15th term from the last is 516.

Given:

• The given A.P. is 6, 12, 18, ..., 600

To find:

• 15th term from the last.

Solution:

Here, a = 6, d = 6, tn = 600

If tn = 6000, then

Second last term = tn - d

Third last term = tn - 2d

In such way,

⇒ Last 15th term = tn - 14d

⇒ Last 15th term = 600 - 14 (6)

⇒ Last 15th term = 600 - 84

⇒ Last 15th term = 516

∴ The 15th term from the last is 516.

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Extra information:

⇒ $\sf{t_{n}=a+(n-1)d}$

⇒ $\sf{S_{n}=\dfrac{n}{2}[2a+(n-1)d]}$

⇒ $\sf{t_{n}=S_{n}-S_{n-1}}$