We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive pseudonymised information about your use of our website. cookie policy and privacy policy.
 
+0  
 
+5
633
7
avatar+869 

Read the following calculations:

$$\\a=b\\
a\times a= a\times b\\
a^2=ab\\
a^2+a^2=a^2+ab\\
2a^2=a^2+ab\\
2a^2-2ab=a^2+ab-2ab\\
2a^2-2ab=a^2-ab\\
2a^2-2ab=1a^2-1ab\\
2(a^2-ab)=1(a^2-ab)\\
2=1$$

Can you spot the miscalculation ?

 Apr 30, 2015

Best Answer 

 #7
avatar+869 
+5

For those who haven't understood, the miscalculation is on the penultimate line :

Since a²=ab, a²-ab=0;

And in the 9th line, I divided each side by a²-ab, so I divided by 0; and as you must now, the division by 0 is impossible.

 May 1, 2015
 #1
avatar
0

a=b

axa=axb

a^2=ab

a^2+a^2=a^2+ab

a^4=a^2+ab

2a^2-2ab=a^2-ab

2a^2-2ab=1a^2-1ab

the correct answer is to this part is: 2a^2-2ab=a^2-ab

so the final answer is a=square root of ab

 Apr 30, 2015
 #2
avatar+100169 
0

I do not think that you have explained what i wrong with the logic :/

 Apr 30, 2015
 #3
avatar+869 
+5

HINT: Since a=b, what is a-b ?

 Apr 30, 2015
 #4
avatar+100169 
0

Yes, that is a good hint :)

 Apr 30, 2015
 #5
avatar+869 
0

Did you spot the miscalculation Melody ?

 Apr 30, 2015
 #6
avatar+100169 
0

Yes i did :)

 May 1, 2015
 #7
avatar+869 
+5
Best Answer

For those who haven't understood, the miscalculation is on the penultimate line :

Since a²=ab, a²-ab=0;

And in the 9th line, I divided each side by a²-ab, so I divided by 0; and as you must now, the division by 0 is impossible.

EinsteinJr May 1, 2015

4 Online Users