please help :)
Is this linear? why or why not?
x: 2 4 6 8
y: 1 5 15 30
thanks :)

Question

please help :)
Is this linear? why or why not? 
x: 2 4 6 8
y: 1 5 15 30
thanks :)

geerky42 · Answer

Can you find slope from given two points?

From table, we have points $(2,1)$ and $(4,5)$. Can you find slope?

Now what about $(4,5)$ and $(6,15)$?

anonymous · Answer

are you asking for the slope? if so, it's 2 and 5/2

anonymous · Answer

@geerky42

anonymous · Answer

There are a few ways to tell if it is linear or not. You could graph the points and see if it form a straight line like and if it does form a straight line it is linear. Here is the points on a graph. https://www.desmos.com/calculator/slvgj1hncp As you can see the points do not form a straight line and looks more like an equation of the form $ y = x^2 $, which is not linear(straight line) If you do not want to graph the points and want to just use the table you provided, You look at all the x and see if it has a constant rate of change and you look at the y values to see if they have a constant rate of change too. If they both have a constant rate of change, it is linear. If they do not, it is not linear. The value of x has a constant rate of change. It is changing by 2. If you look at the y values, it does not have a constant rate of change. The y values go from 5 15 and then all the way to 30, which means there is nothing constant about the y values so since the x values and the y values do not have a constant rate of change, it is not linear.

anonymous · Answer

@geerky42  you cannot tell if a set of points are linear or not by the slope of two points

anonymous · Answer

geerky42 · Answer

No, but with three points, if slopes between them are different, then we can tell that it is not linear. This is what I am trying to saying... @Nixy

geerky42 · Answer

Since slopes are different, it is clear it's not linear.

anonymous · Answer

I get it now :) thanks!

anonymous · Answer

@geerky42 ah I see what you were going for now. With that said, It is a lot easier to look and see if x and y are constant and if they are you know it is linear. This leaves out having to get the slope. Essentially, that is what you are doing by getting the slope. You are checking to see if you have a constant rate of change or not. If the slopes are different, you do not have a constant rate of change On that note, use what works for ya. :-)