1. ## Quadratic Equation for complex dataset

This is really simple for your average person but not me.

Basically I have a dataset involving production of x amount of units and y total costs.

I want to be able to draw a graph, produce an equation and plot the line of best fit on the graph.

How do I find the equation for y on x?

9, 157
11, 215
14, 319
15, 358
16, 400
20, 592
21, 645
25, 885
32, 1397
38, 1929

As you can tell this will produce a curvilinear graph, and from what I've determined from using a calculator, A = 18.087, B=4.66, C=1.200, although it obviously doesn't because the equation won't work.

2. ## Re: Quadratic Equation for complex dataset

Why won't it work?

I get the same values giving $\displaystyle y= 1.2007x^2+4.6627x+18.088$

You can plot it, find the line of best fit and produce this equation easily in ms-excel.

3. ## Re: Quadratic Equation for complex dataset

Oh dear I was using the wrong equation.

You have a + bx + cx2

I had... well I'm not going to tell you what I had hahaha.

Thanks pickslides, sometimes just need some clarity, you know?

One other thing, I'm asked out of YonX and XonY which is the correct alternative, and why? I'm not properly understanding what this is asking.. Do you?

I realise it's YonX because in this case X is the independant variable and Y is the dependant variable but what else is there to say?

4. ## Re: Quadratic Equation for complex dataset

Originally Posted by AmazingThicko

One other thing, I'm asked out of YonX and XonY which is the correct alternative, and why? I'm not properly understanding what this is asking.. Do you?

I realise it's YonX because in this case X is the independant variable and Y is the dependant variable but what else is there to say?
Thats how I would would answer it.