# Multiple Variable Equation, T-89 Titanium

• Feb 19th 2008, 05:47 PM
riker
Multiple Variable Equation, T-89 Titanium
What am I doing wrong?

Problem: -mn-mr=s, solve for m

My input: solve(-mn-mr=s, m)

Output on calculator: 1=-s/mn+mr

Why isn't it displaying it the way I want it to?
• Feb 19th 2008, 05:54 PM
galactus
For goodness sake, you have to multiply the variables, otherwise, the calculator thinks it's one variable.

Enter -m*n-m*r=s

You can't just enter -mn. It has to be multiplied. The calculator is a dumb tool. It doesn't know that.
• Feb 19th 2008, 09:33 PM
riker
Thanks so much. There's another problem I ran into.

Problem: p=4rt-3rs, solve for r

My input: solve(p=4*r*t-3*r*s,r)

Output on calculator: r= -p/3s-4t

I should be set for awhile after I'm helped with this one.
• Feb 19th 2008, 11:09 PM
earboth
Quote:

Originally Posted by riker
Thanks so much. There's another problem I ran into.

Problem: p=4rt-3rs, solve for r

My input: solve(p=4*r*t-3*r*s,r)

Output on calculator: r= -p/3s-4t

$-\frac{p}{3s-t}=\frac{-p}{-(-3s+4t)} = \frac{p}{4t-3s}$