# Help solving/ understanding (Cramers Rule)

• May 17th 2007, 05:39 PM
creatureman
Help solving/ understanding (Cramers Rule)
I need help with this problem? Thanks. The numbers in parenthesis in my book are like exponenets but toward the bottom, kinda like a log number. I did't know how to write that. The answer will be x1= and x2 equals. I cant do it like a regular system of equations problem, its giving me problems. Thanks for any help..

2x(1)+5x(2)=9

5x(1)+7x(2)=8
• May 17th 2007, 06:14 PM
topsquark
Quote:

Originally Posted by creatureman
I need help with this problem? Thanks. The numbers in parenthesis in my book are like exponenets but toward the bottom, kinda like a log number. I did't know how to write that. The answer will be x1= and x2 equals. I cant do it like a regular system of equations problem, its giving me problems. Thanks for any help..

2x(1)+5x(2)=9

5x(1)+7x(2)=8

Define
D =
|2 5|
|5 7|
=2*7 - 5*5 = 14 - 25 = -11

Then
x(1) = (1/D)*
|9 5|
|8 7|
= (1/-11)*(9*7 - 5*8) = (-1/11)*(63 - 40) = -23/11

x(2) = (1/D)*
|2 9|
|5 8|
= (1/-11)*(2*8 - 5*9) = (-1/11)*(16 - 45) = 29/11

-Dan