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Is 1/x+1/1-x = 1/x-x^2 ?

 

Is 1+ 1/x+1 = 2/x+1 ?

 

Is x+ 1/x = x^2+1/x ?

 

Is 1/x-1 - 1/x+1 = 2x/1-x^2 ?

 Jul 19, 2016

Best Answer 

 #2
avatar+9545 
+10

\(\text{I'm gonna type everything in }\LaTeX\)

\(\text{First Question:}\\ \quad \frac{1}{x}+\frac{1}{1-x}\\=\frac{1-x}{x(1-x)}+\frac{x}{x(1-x)}\\=\frac{1-x+x}{x-x^2}\\=\frac{1}{x-x^2}\)

\(\boxed{\color{red}\therefore \frac{1}{x}+\frac{1}{1-x}=\frac{1}{x-x^2}}\)

\(\text{Second Question:}\\ \quad 1+\frac{1}{x+1}\\=\frac{x+1}{x+1}+\frac{1}{x+1}\\=\frac{x+2}{x+1}\)

\(\boxed{\color{red}\therefore 1+\frac{1}{x+1}\neq \frac{2}{x+1}}\)

\(\text{Third Question:}\\\quad x+\frac{1}{x}\\=\frac{x^2}{x}+\frac{1}{x}\\=\frac{x^2+1}{x}\)

\(\boxed{\color{red}\therefore x+\frac{1}{x}=\frac{x^2+1}x}\)

\(\text{Last Question:}\\\quad\frac{1}{x-1}-\frac{1}{x+1}\\=\frac{x+1}{x^2-1}-\frac{x-1}{x^2-1}\\=\frac{x-x+1+1}{x^2-1}\\=\frac{2}{x^2-1}\)

\(\boxed{\color{red}\therefore\frac{1}{x-1}-\frac{1}{x+1}\neq \frac{2x}{1-x^2}}\)

.
 Jul 19, 2016
 #1
avatar+108 
+5

Is 1/x+1/1-x = 1/x-x^2 ?

 

Nope, 1/x+1/1-x = (1-x)/(x+1)

 

Is 1+ 1/x+1 = 2/x+1 ?

 

Nope, 1 + 1/(x+1) = (x+1)/(x+1) + 1/(x+1) = (x+2)/(x+1)

 

Is x+ 1/x = x^2+1/x ?

 

Yes, x + 1/x = x^2/x + 1/x = (x^2+1)/x

 

Is 1/x-1 - 1/x+1 = 2x/1-x^2 ?

 

Nope, 1/(x-1) - 1/(x+1) = (x+1)/(x-1) - (x-1)/(x+1) = ((x+1)-(x-1))/(x^2-1) = 2/(x^2-1)

 

A helpful way to check your answer is to graph the equation (that way you can instantly visually see if they equal each other). 

 Jul 19, 2016
edited by Kreyn  Jul 19, 2016
 #2
avatar+9545 
+10
Best Answer

\(\text{I'm gonna type everything in }\LaTeX\)

\(\text{First Question:}\\ \quad \frac{1}{x}+\frac{1}{1-x}\\=\frac{1-x}{x(1-x)}+\frac{x}{x(1-x)}\\=\frac{1-x+x}{x-x^2}\\=\frac{1}{x-x^2}\)

\(\boxed{\color{red}\therefore \frac{1}{x}+\frac{1}{1-x}=\frac{1}{x-x^2}}\)

\(\text{Second Question:}\\ \quad 1+\frac{1}{x+1}\\=\frac{x+1}{x+1}+\frac{1}{x+1}\\=\frac{x+2}{x+1}\)

\(\boxed{\color{red}\therefore 1+\frac{1}{x+1}\neq \frac{2}{x+1}}\)

\(\text{Third Question:}\\\quad x+\frac{1}{x}\\=\frac{x^2}{x}+\frac{1}{x}\\=\frac{x^2+1}{x}\)

\(\boxed{\color{red}\therefore x+\frac{1}{x}=\frac{x^2+1}x}\)

\(\text{Last Question:}\\\quad\frac{1}{x-1}-\frac{1}{x+1}\\=\frac{x+1}{x^2-1}-\frac{x-1}{x^2-1}\\=\frac{x-x+1+1}{x^2-1}\\=\frac{2}{x^2-1}\)

\(\boxed{\color{red}\therefore\frac{1}{x-1}-\frac{1}{x+1}\neq \frac{2x}{1-x^2}}\)

MaxWong Jul 19, 2016

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