Question

Question to this algebra question?

If f(x)=3x-1 and f(a)=5, what is the value of a

Answer 1

`a=2`

Explanation:

If `f(x)=3x-1`
then `f(a)=3a-1`
and
since we are told `f(a)=5`
we have `3a-1=5`

`color(white)("xxxxx")rArr 3a=6`

`color(white)("xxxxx")rArr a=2`

Answer 2

`a=2`

Explanation:

`f(a)` means that there is some value `a` that when I plug it into `f(x)`, it evaluates to `5`.

In other words, we are essentially being asked what is our input, when our output is `5`?

Let's set `f(x)` equal to `5`:

`3x-1=5`

We can add `1` to both sides and dividing the result by `2` on both sides. We get

`x=2`

Another way we can write this is

`f(2)=5`

When we input `2` into our function, we get `5`. Therefore,

`a=2`

Hope this helps!