Interesting little problem?

The Highlander

Senior Member
Joined
Feb 18, 2022
Messages
1,228
I thought this might be an interesting exercise for some to practise their algebra...

ab = 100
bc = 200
ca = 300


Find the (exact) value of: a + b + c

I'm not asking for any help or suggestions (I already have two separate procedures to get to the answer) I just thought it would be interesting to see how others approach it.

If you can be bothered to tackle it then please post your solution(s) in full.

NB: The answer should be an exact value, ie: left as a (fully simplified) surd multiple not a decimal approximation.
 
From the third equation [imath]c = \dfrac{300}{a}[/imath]

Plug into the second equation and simplify to get [imath]\dfrac{b}{a}=\dfrac{2}{3}[/imath] so [imath]b=\dfrac{2a}{3}[/imath]

Plug into the first equation and simplify to get [imath]a^2=150[/imath]

Square root and back substitute.
 
... or ... multiply all the equations together to get [imath]a^2b^2c^2=6000000[/imath]

Square root and then divide by each equation.
 
Top