Answer:
1) A linear function can be used to represent a line graphed on a chart if there is a straight-line relationship between the x and y variables. It is represented by the equation y = mx + b, where m is the slope and b is the y-intercept.
2) A polynomial function can be used to represent a line graphed on a chart if the relationship between the x and y variables is more complex and not linear. It is represented by the equation y = ax^n + bx^(n-1) +...+ z, where a, b, ... , z are constant coefficients.
3) An exponential function can be used to represent a line graphed on a chart if the relationship between the x and y variables is exponential. It is represented by the equation y = ab^x, where a and b are positive constants.