Every function is a rule which tells you how to associate inputs and outputs. The input, also known as independent variable, is often indicated with the letter
, while the output, also known as dependent variable, is often indicated with the letter
.
With this notation, we write
, read "y is a function of x", in the sense that the value of the variable y depends on the value of the variable x, and f is the function that tells you how y depends on x.
In your example, you have
, which means "subtract four times the input (4x) from 2"
So, it doesn't matter which input you chose (i.e. the value for x), because you will always have to behave this way:
- Pick an input value, x
- Multiply it by four to get 4x
- Subtract this number from 2: 2-4x
Here are some examples of explicit calculations: if I choose
and input, the workflow will be
- Pick an input value, 2
- Multiply it by four to get 8
- Subtract this number from 2: 2-8=-6
So, if the input is 2, the output is -6
Similarly, if we choose
as input, we have:
- Pick an input value, 0
- Multiply it by four to get 0
- Subtract this number from 2: 2-0=2
So, if the input is 0, the output is 2. And so on: for every possible value for x you have the correspondant value for y, with the function f telling you how to associate one with the other.
Answer
Write an expression for the number of pencils Maggie gives to jamil.
To prove
Let us assume that the number of pencils Katie have = x
As given
Katie gives Maggie half of her pencils.

As given
Maggie keeps 5 and gives the rest to jamil.
Thus

Therefore the expression for the number of pencils Maggie gives to jamil are
.
Can you please include a pic
X = 47
you subtract 133 from 180
Answer:
Ans: 6c+3=45
6c=45-3
6c/6=42/6
C=7
So my correct answer is C=7