Find $a,\ b$ and $c$ such that the following numbers are in A.P. $a,\ 7,\ b,\ 23,\ c$

Given: An A.P. $a,\ 7,\ b,\ 23,\ c$.

To do: To find $a,\ b$ and $c$.

Solution:

$a,\ 7,\ b,\ 23,\ c$ are in AP

Therefore, $7-a=d$ ......$( i)$

$b-7=d$   ....... $( ii)$

$23-b=d$  ....... $( iv)$

$c-23=d$  ....... $( v)$

From $( i)$ and ( ii)$

$7-a=b-7$

$\Rightarrow -b-a=-14$

$\Rightarrow a+b=14$ ....... $( vi)$

From $( ii)$ and $( iv)$

$b-7=23-b$

$\Rightarrow b+b=23+7$

$\Rightarrow 2b=30$

$\Rightarrow b=\frac{30}{2}$

$\Rightarrow b=15$, Put this in equation $( vi)$

$a+15=14$

$\Rightarrow a=14-15=-1$

Now, from $( iv)$ and $( v)$

$c-23=23-b$

$\Rightarrow c-23=23-15$

$\Rightarrow c-23=8$

$\Rightarrow c=8+23$

$\Rightarrow c=31$

Thus, the values of $a,\ b$ and $c$ are $-1,\ 15$ and $31$ respectively.

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Updated on: 10-Oct-2022

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