# Thread: Simple Linear Algebra Question

1. ## Simple Linear Algebra Question

Equation: $3t= \frac{5}{4}$

Step 1: $t=\frac{1}{3}*\frac{5}{4}$

My question concerns this step. To isolate the variable "t" you divide by 3. It seems that should read $t=\frac{5}{4} \div \frac{1}{3}$ however that leads to an incorrect answer. The correct way to do this apparently is $t=\frac{1}{3}*\frac{5}{4}$. Why do you multiply by 1/3? When you isolate "t" you divide by 3.

Thanks for the clarification.

2. ## Re: Simple Linear Algebra Question

Originally Posted by allyourbass2212
My question concerns this step. To isolate the variable "t" you divide by 3. It seems that should read $t=\frac{5}{4} \div \frac{1}{3}$
No, here you are trying to divide by $\textstyle\frac13,$ not 3. Dividing by three is the same as multiplying by one-third:

$\frac54\div3 = \frac54\div\frac31 = \frac54\cdot\frac13.$

3. ## Re: Simple Linear Algebra Question

Originally Posted by Reckoner
No, here you are trying to divide by $\textstyle\frac13,$ not 3. Dividing by three is the same as multiplying by one-third:

$\frac54\div3 = \frac54\div\frac31 = \frac54\cdot\frac13.$
Thanks, to be clear then this is for all linear algebra for instance

Equation: $2x = 6$
Step 1: $x= \frac{6}{1} \cdot \frac{1}{2}$
$x= 3$

4. ## Re: Simple Linear Algebra Question

Originally Posted by allyourbass2212
Equation: $2x = 6$
Step 1: $x= \frac{6}{1} \cdot \frac{1}{2}$
$x= 3$
Correct. You could work this either way, by dividing both sides by 2 or by multiplying both sides by the reciprocal $\textstyle\frac12.$ You get the same result regardless.

5. ## Re: Simple Linear Algebra Question

attraction signs

tutorial.math.lamar.edu/Classes/LinAlg/LinAlg.aspxHere are my online notes for my Linear Algebra course that I teach here at ... Sometimes a very good question gets asked in class

6. ## Re: Simple Linear Algebra Question

Simple linear algebra is a integrated part of mathematics. sometimes students ask a difficult and logical questions in the class.

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