Question

if the common difference of an ap is 5 then a15 - a11 is equal to​

Answer 1

Here you go, I hope it helps

Answer 2

The value of $a_{15} - a_{11}$ is 20.

Given:

Common difference, d = 5.

To Find:

Using the given value of common difference, we have to find the value of $a_{15} - a_{11}$.

Solution:

If first term of an AP is $a_{1}$ and $d$ is the common difference then $n^{th}$ term of the AP is given by:

$a_{n} = a_{1} + (n-1).d$

Then, $a_{15} = a_{1} + 14$ × $5$

$a_{15} = a_{1} + 70.$

Similarly, $a_{11} = a_{1} + 10$ × $5$

$a_{11} = a_{1} + 50.$

∴, $a_{15} - a_{11} = (a_{1} + 70) - (a_{1} + 50) = 20.$

Hence, if the common difference of an AP is 5 then $a_{15} - a_{11}$ is equal to 20.

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