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While squaring a non-zero number John added the number to itself instead of multiplying with itself. John still got the correct answer. Find the number John started with.

 Jan 14, 2021
 #1
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Let a be the number

 

a^2  =  a +  a

 

a^2  = 2a

 

a^2 -  2a  = 0

 

a( a - 2)  = 0

 

Since a is non-zero, then    a - 2  =  0     ⇒    a   = 2

 

2^2  = 2 + 2  

 

  4    =     4

 

 

 

 

 

 

cool cool cool

 Jan 14, 2021

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