Excel for Marketing Managers

Solving Systems of Equations

Solving

Systems of

Equations

a. So, before you begin, enter a 1, 2, and 361 into cells K9, N9, and Q9, re-

spectively. Then enter 2, 1, and 362 into cells K11, N11, and Q11. In

Box A, enter a 1, and in Box B, enter a 2. This way, you can check to see

if you are getting the correct results with your formulas as you go along.

b. In row 13, you need formulas that will multiply the value in Box A by

the coefficients in Equation 1. In cell K13, type in the following formula:

=$i$13*k9

This tells Excel to multiply the value in cell I13 by the value in K9. The

$i$13 tells Excel that you have made an absolute reference to I13 that

will not change as we copy the formula.

c. Click once on cell K13 and press Ctrl+C to start the copy process. Click

on cell N13 and press Ctrl+V, and then click Q13 and press Ctrl+V to

paste the copied formula. The three cells should contain the numbers 1,

2, and 361.

d. Now click on cell K15 and type in the following formula:

= $i$15*K11

Press Ctrl+C to copy, and paste into N15 and Q15. These three cells

should now contain a 4, 2, and 724.

e. This step subtracts the equation in row 15 from the equation in row 13.

Click on cell K17 and type in the following formula:

=k13-k15

Copy and paste into N17 and Q17. The cells should contain -3, 0, and -

363.

f. Box C is used to tell Excel what you want to use to divide the equation

in row 17. Since the x-coefficient of that equation is currently -3, enter

that into Box C.

g. In cell Q20, enter the following formula:

=Q17/Q20

The number displayed in this cell should be 121.