Help please, I am bad at f(x), and I need to complete this particular question.

Could be lots of things.

Do you want the equartion of the LINE that goes through those 2 points?

You got it - Sorry for my bad explanation.

A (-1 -4) B (-5 -1) what is f(x) ?

I have my own method with these.  It is slightly mathematically floored but it replaces a few different formulas

\(\begin{align*} gradient&=gradient\\ &\\ \frac{y-y_1}{x-x_1}&=\frac{y_2-y_1}{x_2-x_1}\\ &\\ \frac{y--4}{x--1}&=\frac{-1--4}{-5--1}\\ &\\\frac{y+4}{x+1}&=\frac{-1+4}{-5+1}\\ &\\\frac{y+4}{x+1}&=\frac{3}{-4}\\ &\\-4(y+4)&=3(x+1)\\ &\\-4y-16&=3x+3\\ &\\0&=3x+4y+16+3\\ &\\3x+4y+19&=0\\ \end{align*} \)

Went through it with my tutor and he told me it was correct, as well as explained me as to why it was. Therefore, I've learned something, thanks to you. Hope you got a great day in front of you

You are very welcome :))