We assume you want the tangent to the parabola y = x² -3x +1 at the given point. The slope is found using the derivative of the function at that point.
y' = 2x -3
At x=3, the slope is ...
y' = 2(3) -3 = 3
The equation of the line through point (3, 1) with a slope of 3 is ...
y -1 = 3(x -3) . . . . use the point-slope form of the equation for a line