A Simple Linear equation in 1 Variable!

Algebra Level pending

Positive real numbers a a , b b , and c c are such that a b c = 1 abc = 1 . Find the value of x x satisfying the equation below.

2 a x a b + a + 1 + 2 b x b c + b + 1 + 2 c x c a + c + 1 = 1 \frac{2ax}{ab + a + 1} + \frac{2bx}{bc + b +1} + \frac{2cx}{ca + c + 1} = 1


The answer is 0.5.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Nitin Kumar
Apr 13, 2020

From a b c = 1 abc=1 , the given equation can be changed in the form

2 a b c x ( a b ) ( b c ) + a ( b c ) + b c + 2 b x b c + b + 1 + 2 b c x ( c a ) ( b ) + c ( b ) + b = 1 \frac{2abcx}{(ab)(bc)+a(bc)+bc} + \frac{2bx}{bc+b+1} +\frac{2bcx}{(ca)(b)+c(b)+b}=1 ,

2 x b + 1 + b c + 2 b x b c + b + 1 + 2 b c x b c + b + 1 = 1 \frac{2x}{b+1+bc} + \frac{2bx}{bc+b+1} + \frac{2bcx}{bc+b+1} = 1 ,

2 ( b c + b + 1 ) x b c + b + 1 = 1 \frac{2(bc+b+1)x}{bc+b+1}=1 ,

Yielding x = 1 2 = 0.5 x= \frac{1}{2} = 0.5

great question as well as solution. but the best thing is the simplicity of the answer! BTW what is actually surprising is that you know so much at such a young age. Bravo!

Kumudesh Ghosh - 1 year, 2 months ago

Log in to reply

Thanks for the nice comment Kumudesh!

Nitin Kumar - 1 year, 1 month ago
Chew-Seong Cheong
Apr 13, 2020

2 a x a b + a + 1 + 2 b x b c + b + 1 + 2 c x c a + c + 1 = 1 2 a x ÷ a ( a b + a + a b c ) ÷ a + 2 b x b c + b + 1 + 2 c x × b ( c a + c + 1 ) × b = 1 Note that a b c = 1 2 x b + 1 + b c + 2 b x b c + b + 1 + 2 b c x ( 1 + b c + b ) = 1 2 x ( 1 + b + b c ) b c + b + 1 = 1 2 x = 1 x = 1 2 = 0.5 \begin{aligned} \frac {2ax}{ab+a+1} + \frac {2bx}{bc+b+1} + \frac {2cx}{ca+c+1} & = 1 \\ \frac {2ax\blue{\div a}}{(ab+a+\blue{abc})\blue{\div a}} + \frac {2bx}{bc+b+1} + \frac {2cx\red{\times b}}{(ca+c+1)\red{\times b}} & = 1 & \small \blue{\text{Note that }abc = 1} \\ \frac {2x}{b+1+bc} + \frac {2bx}{bc+b+1} + \frac {2bcx}{(1+bc+b)} & = 1 \\ \frac {2x(1+b+bc)}{bc+b+1} & = 1 \\ 2x & = 1 \\ \implies x & = \frac 12 = \boxed{0.5} \end{aligned}

Great solution as always. and.. you forgot a bracket on the numerator of the third last line. Thanks!

Mahdi Raza - 1 year, 1 month ago

Log in to reply

Thanks. Got it fixed.

Chew-Seong Cheong - 1 year, 1 month ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...