To translate the function $f(x) = -9x + 3$ one unit up, you add 1 to the entire function. This is because a vertical translation involves adjusting the output (or y-value) of the function.

The new function will be:

$f(x) = -9x + 3 + 1$

Simplifying:

$f(x) = -9x + 4$

So, the function after a translation of 1 unit up is $f(x) = -9x + 4$.

Would you like further details or have any questions?

Here are 5 related questions:

1. How do you translate a function vertically by any number of units?
2. What happens when you translate a function horizontally instead of vertically?
3. How does the slope of a linear function affect its graph?
4. What is the difference between translating a function up and down?
5. How do you find the y-intercept of a linear function like $f(x) = -9x + 4$?

Tip: Translating a function vertically doesn't change its slope, only its position on the y-axis.