Help with a simple algebra problem

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  • Thread starter MartinJH
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  • #1
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Hi

I'm trying to solve;
t / 2t-s = 3s
for t
the answer I get is; t = -3s^2/1-6s. However, the answer given is; 3s^2/6s-1

The steps I use are;
t = 3s(2t - s)
t = 6st - 3s^2
t - 6st = -3s^2
t(1 - 6s) = -3s^2
t = 3s^2 / 1 - 6s

If someone could point out where I'm going wrong that would be great, thank you.
 

Answers and Replies

  • #2
14,410
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Hi

I'm trying to solve;
t / 2t-s = 3s
for t
the answer I get is; t = -3s^2/1-6s. However, the answer given is; 3s^2/6s-1

The steps I use are;
t = 3s(2t - s)
t = 6st - 3s^2
t - 6st = -3s^2
t(1 - 6s) = -3s^2
Here. You switched the sign on the right but not on the left.
t = 3s^2 / 1 - 6s

If someone could point out where I'm going wrong that would be great, thank you.
 
  • #3
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I'm trying to solve;
t / 2t-s = 3s
for t
the answer I get is; t = -3s^2/1-6s. However, the answer given is; 3s^2/6s-1
Use parentheses! When you write mathematical expressions on a single line, and have fractions with numerators or denominators that have multiple terms, you absolutely need to use parentheses.

Textbooks can have things like ##\frac t {2t - s}##, where it's clear which terms are in the denominator, but when you write t/2t - s, it really means ##\frac t 2 t - s##, which is probably not what you meant.
Also, what you wrote as 3s^2/1 - 6s would reasonably be interpreted to mean ##3\frac {s^2} 1 - 6s.

I used LaTeX for format the two expressions. If you don't use LaTeX (we have a very good tutorial here -- https://www.physicsforums.com/help/latexhelp/), the equation you started with should be written as t/(2t - s) = 3s, and the solution you got should be written as t = 3s^2/(1 - 6s).
 
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PeroK
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Hi

I'm trying to solve;
t / 2t-s = 3s
for t
the answer I get is; t = -3s^2/1-6s. However, the answer given is; 3s^2/6s-1

If someone could point out where I'm going wrong that would be great, thank you.
Those are the same answer.
 
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