Excel - graph of y=ax+b in excel

Asked By kam on 03-Oct-07 07:59 PM
Please tell me how I can draw graph of y-ax+b in Excel ?!




Joe replied on 03-Oct-07 08:20 PM
Excel doesn't take inputs in the form of a line which is y=ax + b.  It simply
requires a list of the x points and y points.  Excel automatically calculates
the a value and the b value.

you enter points in two rows or two columns

Col A            Col B
(x values)     (Y values)

1                   4
2                   7


The a value is the slope = (delta y)/(delta x) = (7 -4)/(2 -1) = 3
Y = ax + b
7 = (2*3) + b
b = 1
Excel does the calculation above automatically.
kam replied on 03-Oct-07 09:20 PM
Well,
I have the following values :

I = 0 ,0.17, 0.25 , 0.42, 0.5 , 0.75 ,0.83, 1 A
V = 0, 20 , 40, 60 ,80 , 100 , 120  V
V=0 ,I=0
V=20,I=0.17
V=40 ,I=0.25
V=50 ,I=0.42
V=60 ,I=0.5
V=80  ,I=0.75
V=100 ,I=0.83
V=120 ,I=1

V=IR    R=120  (V= 120i )>>>>    y=ax+b
V=x
I=y

What would I do ?!
Please help me.
Joe replied on 03-Oct-07 09:36 PM
1) Enter data in cells starting at row 1 below

Col A       Col B
0	0
20	0.17
40	0.25
50	0.42
60	0.5
80	0.75
100	0.83
120	1

2) From worksheet menu select Insert - Chart
3) Select X-Y Scatter
4) Select scatter char with just points no line
5) Press Next twice
6) Enter chart title: volts vs Current
7) Enter X-Axis: Volts
8) Enter Y Axis Amps
9) Press Finish
10) Right click on one of the points in graph
11) Select Add Trend Line
12) Select Linear
13) Press Options Tab
14) Select Display Equation on Chart Box
15) Press OK
You equation is y = 0.0086x - 0.0154
a = .0086
b = .0154
kam replied on 04-Oct-07 05:55 AM
Ur the fantastic,
appreciate it.
kam replied on 04-Oct-07 05:55 AM
u r fantastic,

Appreciate it.