Question

Find the equation that represents the proportional relationship in this graph, for

y in terms of

x.

Answer 1

y = -3x

Explanation:

The definition of an equation with a proportional relationship with another is that they need to intersect at a 90° angle.

To do this you just have to multiply the slope of the line by its negative reciprocal. So you have to flip the fraction (reciprocal) and then multiply it by -1.

Find the equation of the line:

The line starts at the origion so the y-intercept (b value) is equal to 0.

Looking at slope we can tell that the line has a point at (0, 0) and (3, 1).

The slope between these points is as follows

`(1 - 0)/(3 - 0)`

So the equation for the first line is y = 1/3x

We then flip the fraction and multiply by -1 to get its proportional line.

y = 1/3x

y = 3x

y = -3x