Question

If x = 3, then find the value of 3x + 1.

Answer 1

Hint: For solving this problem, first meet the right to form f(x) from the given problem statement. By obtaining f(x), we can simply put the value of x as 3 to obtain f (3). By using this methodology, we easily obtain the required value of expression.
Complete step-by-step answer:
According to the problem statement, we are required to find the value of 3x + 1 when x equals to 3.
Now, first forming the expression as a function of x. So, we get
$f(x)=3x+1,x\in R$
To evaluate any particular value of x, we simply replace x in f(x). Hence to evaluate the value at x equals to 3, we simply replace x by 3. This can be shown mathematically as:
$\begin{align}
  & f(x=3)=3\times 3+1 \\
 & f(3)=9+1 \\
 & f(3)=10 \\
\end{align}$
Hence, f (3) is the required value of the expression. Therefore, the value of 3x + 1 is 10.
Note: This is a direct problem which can be alternatively solved by simply replacing x as 3 in 3x + 1. For obtaining resultant values corresponding to different values of x, the method of forming a function of x is reliable and easy to operate, having less chances of errors.