Sometimes you do, sometimes you don't.
In the Euclidean plane. a straight line is the shortest distance between two points. Also, the equation of a straight line is simpler than that of curved lines.
Finally, there is the Occam Rule which can be put as follows: when there are lots of possibilities to choose from, go for the simplest one. There are infinitely many curves (including a straight line) that can go through a pair of points.
A frequency curve is a graph obtained by joining the points of a frequency polygon freehand smoothly.
when two or more points can create a straight line
if it touches at three points it is a straight line. Since it is also an asymptote, it will be a straight horizontal line (zero slope)
A continuous linear function produces a straight line graph that can be extended indefinitely in either direction. If the two ordered pairs are plotted on a graph then a straight line can be drawn joining these points. If that line is extended beyond both ends then there are no set limits and the function becomes continuous.
a line of best fit
The definition is any chart where one or more points lie off the straight line joining the other points.
linear graph
A Linear graph
a straight line
a straight line
A non-linear graph.
nonlinear graph
nonlinear graph.
A frequency curve is a graph obtained by joining the points of a frequency polygon freehand smoothly.
There is no specific name. It could be a non-linear graph, or a scatter graph.
when two or more points can create a straight line
if it touches at three points it is a straight line. Since it is also an asymptote, it will be a straight horizontal line (zero slope)