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Multiplication Quickie (Posted on 2024-06-21) Difficulty: 3 of 5
Each of a, b, and c is a real number that satisfy:
a-b = a*b*c
b-c = a*b*c
c+a = 3*a*b*c
Using only p&p, how fast can you come up with all possible values of a*c

See The Solution Submitted by K Sengupta    
Rating: 4.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Some Thoughts Possible Solution | Comment 1 of 2
Let abc=x

a-b=x, b-c=x, a+c=3x

Solutions: a=5c, b=3c.

Substitution:

2c=15c^3, 2=15c^2,  c=+-sqrt(2/15), 
and b=+-sqrt(30)/5, b=+-sqrt(6/5) 
and a=+-sqrt(30)/3, a=+-sqrt(10/3)

The hardest part was simplifying the square roots for b and c, say 15 mins in all.

Note to self: next time, finish reading the problem before starting the clock.

Edited on June 22, 2024, 11:36 pm
  Posted by broll on 2024-06-22 02:17:01

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