Question

How do you evaluate the function f(x) = 3x-7 for f(5)?

Answer 1

Hint: This type of problem is based on the concept of functions with one variable. First, we have to consider the function with the variable x. Here, we have to find the value of the function when x is equal to 5. Substitute x=5 and do necessary calculations. Simplify the given function by substitution and find the value of f(5) which is the required answer.

Complete step by step solution:
According to the question, we are asked to find the value of f(x) = 3x-7 for f(5).
We have been given the function is f(x) = 3x-7. -----(1)
The given function is with one variable x.
When the variable is equated to a constant, we have to substitute the constant in place of the variable in the function to find the required value.
Here, we have to find the value of f(5).
To find the value of f(5), we have to substitute x equal to 5 in the considered function (1).
On substituting x=5 in the function (1), we get
\[f\left( 5 \right)=3\times 5-7\]
We know that 3 multiplied by 5 is equal to 15.
On substituting the value, we get
\[f\left( 5 \right)=15-7\]
On further simplification, we get
\[f\left( 5 \right)=8\]
Therefore, the value of the function \[f\left( x \right)=3x-7\] for f(5) is 8.

Note:
Whenever you get this type of problem, we should do the necessary calculations correctly to get the accurate answer. When we substitute x=5, the function is not f(5)=35-7. It is \[f\left( 5 \right)=3\times 5-7\]. When f(5) is asked to find, we should not multiply the whole function by 5, instead substitute 5 in place of x. Avoid calculation mistakes based on sign conventions.