Extreme rationalizing 2
A = 2 + 3 + 5 3 + 5 + 2 − 3 − 5 3 − 5
If A can be expressed as a + b c for non-negative integers a , b , c with c square free, then find the value of a + b + c .
The answer is 4.
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1 solution
Didn't understand the second step
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( 1 + 5 ) 2 = 6 + 2 5 , ( 5 − 1 ) 2 = 6 − 2 5 .
jaja, really good solution.
We have:
2 A = 2 + 6 + 2 5 3 + 5 + 2 − 6 − 2 5 3 − 5
= 2 + ( 1 + 5 ) 3 + 5 + 2 − ( 5 − 1 ) 3 − 5 = 2
Hence, A = 2 2 .