To determine the common difference of the arithmetic progression (A.P.) consisting of the numbers \(x\), \(x+4\), and \(x+8\), we need to recall the property of an arithmetic progression where consecutive terms have a constant difference.
In an arithmetic progression, if \(a_1\), \(a_2\), \(a_3\), ..., are the terms, then the common difference \(d\) is given by:
\(d = a_2 - a_1 = a_3 - a_2\)
Now, apply this to the given numbers:
Here, \(a_1 = x\), \(a_2 = x + 4\), and \(a_3 = x + 8\).
Therefore, the common difference can be calculated as follows:
Both calculations yield the same common difference, which is 4. Therefore, the common difference \(d\) for the arithmetic progression is:
\(4\)
Thus, the correct answer is 4.
Consider an A.P. $a_1,a_2,\ldots,a_n$; $a_1>0$. If $a_2-a_1=-\dfrac{3}{4}$, $a_n=\dfrac{1}{4}a_1$, and \[ \sum_{i=1}^{n} a_i=\frac{525}{2}, \] then $\sum_{i=1}^{17} a_i$ is equal to