System of linear equations - solve with 3 variables?

[k9handler]

thanks for your efforts, we are working on the TI82 and attempting it...I will let you know if we figure it out.

[speedracing944]

This is the method I learned in Math 320 Differential equations and linear algebra except I had to do it by hand and with a clear mind (unlike now )

If she learns this now she will be in great shape come college.

Speedy

[k9handler]

ha ha this is my class. She is a senior this coming year and I agree she is on a good path for college.

[DavidB911]

Another and I think easier method (w/o using a calculator to solve it for you) is to use Cramers Rule (well, not for 3 unknowns, but its not too difficult). First, you put the variable coefficients into a 3x3 matrice.

31 12 -24
18 24 1
12 -6 4

det of ^ = 11946

Finding this makes things later easier.

then substitue the 4th column into the varible you want to solve for.

105 12 -24
77 24 1
5 -6 4

det of ^ = 21042

Then you take and the "determinent of the variable" matrice and divide the "determinent of the original" matrice. ie. 21042/11946~=1.7614

Do that for y and z.
the answers should be y=1.9345 and z=-1.1326.

This may be the method your child learned in class, but i'm not sure since I wasn't there. Some people on here wouldn't be able to do simple math w/o a calculator