Math CentralQuandaries & Queries


Question from becca, a student:

Find the function value
F(1)if f(x)=x+3

Hi Becca,

Often we can think of the functions we see as calculating machines. You give the function (machine) and the function performs some operation on the number and gives you the result. In algebra we use a letter, often the letter x to describe the calculation that the function performs. For example suppose a function operates with this rule.

Give me a number, I will multiply it by 3 and then subtract 2.

If I decide to name the function g then algebraically I would write this

g(x) = 3x - 2.

So x is the number you give to the function and "3x - 2" says multiply the number by 3 and then subtract 2. Hence if you give the number 1 to this function the result is 3 × 1 - 2 = 1. We write this

g(1) = 3 × 1 - 2 = 1.


g(4) = 3 × 4 - 2 = 10.

Now find f(1) where the function f is described by f(x) = x + 3

Write back if you need more assistance,

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