# Algebraic Fractions

• Jun 16th 2011, 08:38 PM
JanoD
Algebraic Fractions
R = -0.0075t+3.85. Solve for t.

Here's my working.

R = -0.0075t+3.85
R-3.85 = -0.0075t
-t = R-3.85/-0.0075
t = R-3.85/0.0075

I thought this was correct but in the answer book on the very last step, I am wrong:

t = 3.85-R/0.0075

Why is this?
• Jun 16th 2011, 08:46 PM
Also sprach Zarathustra
Re: Algebraic Fractions
Quote:

Originally Posted by JanoD
R = -0.0075t+3.85. Solve for t.

Here's my working.

R = -0.0075t+3.85
R-3.85 = -0.0075t
-t = R-3.85/-0.0075
t = R-3.85/0.0075

I thought this was correct but in the answer book on the very last step, I am wrong:

t = 3.85-R/0.0075

Why is this?

$\displaystyle R = -0.0075t+3.85$

$\displaystyle R - 3.85 = -0.0075t$

Dividing by:$\displaystyle -0.0075$

$\displaystyle \frac{R - 3.85}{-0.0075}=t$
• Jun 17th 2011, 01:27 AM
HallsofIvy
Re: Algebraic Fractions
Quote:

Originally Posted by JanoD
R = -0.0075t+3.85. Solve for t.

Here's my working.

R = -0.0075t+3.85
R-3.85 = -0.0075t
-t = R-3.85/-0.0075

Here is your error. You divided both sides by -0.0075 and $\displaystyle \frac{-0.0075t}{-0.0075}= t$, not -t.

Quote:

t = R-3.85/0.0075

I thought this was correct but in the answer book on the very last step, I am wrong:

t = 3.85-R/0.0075

Why is this?