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Find A30 − A20 For the A.P. A,A + D, a + 2d, a + 3d, ... - Mathematics

Find a30 − a20 for the A.P.

a,a + d, a + 2d, a + 3d, ...

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Solution

A.P. a,a + d, a + 2d, a + 3d, ...

Here

First term (a) = a

Common difference of the A.P (d) = a + d -a = d

Now as we know

`a_n= a + (n - 1)d`

Here we find `a_30` and `a_20`

So for 30 th term

`a_30 = a + (30 - 1)d`

`= a + (29)d`

Also for 20 th term

`a_20 = a + (20 - 1)d`

= a - (19)d

So,

`a_30 - a_20 = (a + 29d) - (a + 19d)`

= a + 29d - a - 19d

= 10d

Therefore for the given A.P `a_30 - a_20 = 10d`

  Is there an error in this question or solution?
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APPEARS IN

RD Sharma Class 10 Maths
Chapter 5 Arithmetic Progression
Exercise 5.4 | Q 20.2 | Page 25
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