Difference between revisions of "Proof that 2=1"

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1) <math>a = b</math>. Given.
 
1) <math>a = b</math>. Given.
 +
 
2) <math>a^2 = ab</math>. Multiply both sides by a.
 
2) <math>a^2 = ab</math>. Multiply both sides by a.
 +
 
3) <math>a^2-b^2 = ab-b^2</math>.  Subtract <math>b^2</math> from both sides.
 
3) <math>a^2-b^2 = ab-b^2</math>.  Subtract <math>b^2</math> from both sides.
 +
 
4) <math>(a+b)(a-b) = b(a-b)</math>.  Factor both sides.
 
4) <math>(a+b)(a-b) = b(a-b)</math>.  Factor both sides.
 +
 
5) <math>(a+b) = b</math>. Divide both sides by <math>(a-b)</math>
 
5) <math>(a+b) = b</math>. Divide both sides by <math>(a-b)</math>
 +
 
6) <math>a+a = a</math>.  Substitute <math>a</math> for <math>b</math>.
 
6) <math>a+a = a</math>.  Substitute <math>a</math> for <math>b</math>.
 +
 
7) <math>2a = a</math>.  Addition.
 
7) <math>2a = a</math>.  Addition.
 +
 
8) <math>2 = 1</math>.  Divide both sides by <math>a</math>.
 
8) <math>2 = 1</math>.  Divide both sides by <math>a</math>.
 +
 +
Wait, What?

Revision as of 18:30, 27 June 2019

1) $a = b$. Given.

2) $a^2 = ab$. Multiply both sides by a.

3) $a^2-b^2 = ab-b^2$. Subtract $b^2$ from both sides.

4) $(a+b)(a-b) = b(a-b)$. Factor both sides.

5) $(a+b) = b$. Divide both sides by $(a-b)$

6) $a+a = a$. Substitute $a$ for $b$.

7) $2a = a$. Addition.

8) $2 = 1$. Divide both sides by $a$.

Wait, What?