Question

If \[2x + 3 = x - 4\], then the value of \[x\] is
A) \[ - 4\]
B) \[ - 7\]
C) \[ - 9\]
D) \[ - 10\]

Answer 1

Hint: In order to solve for any unknown term from an equation the unknown term needs to be isolated on one side of the equation and the constants to the other side. In this problem bring all the terms containing \[x\] to one side and the constants to the other side and solve.

Complete step by step solution:
In the question we are provided with a linear equation. From this equation the value of \[x\] needs to be found out.
Given:
\[2x + 3 = x - 4\]
In L.H.S. there is a term containing the variable \[x\] and a constant, in the R.H.S. Also there is a term containing the variable \[x\] and a constant. So bring all the terms containing \[x\] to the L.H.S.
\[\therefore \]\[2x + 3 = x - 4\]
\[ \Rightarrow \] \[2x - x = - 4 - 3\]
Simplifying:
\[ \Rightarrow \] \[x = - \left( {4 + 3} \right)\]
\[ \Rightarrow \] \[x = - 7\].

Hence the value of \[x\] is \[ - 7\]. So, the correct option is, option (b).

Note:
In this question be very careful while changing the sides of the variables and constants and their respective signs. For example while taking \[x\] from R.H.S to L.H.S one can make the mistake of writing \[ + x\] in L.H.S. Also, but that is wrong , on changing sides the sign of \[x\] will change from \[ + \] to \[ - \]. Similarly while moving \[3\] from L.H.S. to R.H.S. it will become \[ - 3\] in R.H.S.