a) \( f(x)=0,8 x+8 \);

Did you know that linear functions like \( f(x) = 0.8x + 8 \) can be represented graphically as straight lines? In this case, the slope is 0.8, which indicates how steep the line is, while the y-intercept is 8, meaning that the line crosses the y-axis at the point (0,8). Grab a graphing tool and see how this function behaves! In practical applications, such a function can model real-world scenarios like budgeting. For example, if you’re calculating total expenses where you have a base fee of $8 with an additional $0.80 per item purchased, \( f(x) \) will help you quickly see how much you’ll spend as you buy more items. It's like a shopping calculator but in the form of a line!