Question

The solution of the equation

$( x + 1 ) + ( x + 4 ) + ( x + 7 ) + \ldots \ldots \ldots + ( x + 28 ) = 155$ is.

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (A)

1

Answer 2

We have

Let $n$ be the number of terms in the A.P. on L.H.S. Then $x + 28 = ( x + 1 ) + ( n - 1 ) 3$ $\Rightarrow$ $n = 10$

$\therefore$ $( x + 1 ) + ( x + 4 ) + \ldots \ldots + ( x + 28 ) = 155$

$\Rightarrow$ $\frac { 10 } { 2 } [ ( x + 1 ) + ( x + 28 ) ] = 155$ $\Rightarrow$ $x = 1$.