Question

PLZ HELP Use the graph to write an equation of the line.

Answer 1

Answer:

y = 55x

Step-by-step explanation:

This is a straight line graph - this means that the equation of the line can be written in the form y = mx + c, where m = the gradient of the line (how quickly it goes up or down) and c is a constant that determines how high or low the 'origin' of the line is.

The first thing to do is to find the m, or gradient, of the line. This can be done using a simple rule that you must remember: rise over run. What this means is, between two points on the line, you must find how much higher the second point is than the first, then divide this by how far right the second point is to the first.

Let's do the calculations:

Rise = 165 - 55 = 110 (point 2 is 110 units higher than point 1)

Run = 3 - 1 = 2 (point 2 is 2 to units to the right of point 1)

Now divide these, rise over run:

110 / 2 = 55, therefore m = 55.

So now we have m, but how do we find c? We can substitute the x and y of one the points on the line into y = mx + c, alongside our value of m = 55.

I'll use point 1 for this example, as the numbers are smaller (y = 55, x = 1).

55 = 55 * 1 + c

Now, solve the equation to find c:

55 = 55 + c

0 = c

c is therefore 0! But this is not always the case, so watch out...

We have found all the numbers we need, but don't forget to write out the full equation! After having calculated m and c, we know the equation of the line is y = 55x (+ 0).