how does a graph show a proportional relation ship

Question

PLEASE HELP IM BEATING MY HEAD UP

Answer 1

A graph shows an independent variable (usually x) and a dependent variable (usually y).  We say y is a function of x.  So, for each allowable value of x the function has one or no value of y.

 

For a line, the equation can be expressed in slope-intercept form as y=mx + b, where m is the slope and b is the y-intercept.  The slope is often called "rise over run" because it measures the increase in the y-values divided by the increase in the x-values.  Given two points, the slope is  (y₂ - y₁) / (x₂ - x₁).

 

Now, a proportion can also be expressed as a fraction:   for example, 4 out of 5 is 4/5 or 0.80 or 80%.  That "4/5" looks just like the slope we just mentioned.

 

For a graph, the proportional relationship between y and x is the slope of the graph.

Answer 2

If there is a proportional relationship between two variables x and y, a graph of y versus x would be a straight line.