How do you solve #\frac { x } { 4} + \frac { 2x } { 9} = \frac { 9x - 1} { 9x }#?

1 Answer
Dec 10, 2016

#x = 2/17# and #x = 2#

Explanation:

First, we should put each fraction over a common denominator so we can add and subtract them problem. In this case a common denominator for each fraction would be #36x#. We need to multiply each fraction by the correct form of #1# to have them each over a common denominator:

#(9x)/(9x) * (x/4) + (4x)/(4x) * (2x)/9 = 4/4*((9x - 1))/(9x)#

#(9x^2)/(36x) + (8x^2)/(36x) = (4(9x - 1))/(36x)#

#(17x^2)/(36x) = (36x - 4)/(36x)#

We can now multiply each side of the equation by #36x# to eliminate the fractions while keeping the equation balanced:

#(36x) * (17x^2)/(36x) = (36x) * (36x - 4)/(36x)#

#cancel((36x)) * (17x^2)/cancel((36x)) = cancel((36x)) * (36x - 4)/cancel((36x))#

#17x^2 = 36x - 4#

We can now manage the equation to be a quadratic in standard for while keeping the equation balanced:

#17x^2 - 36x + 4 = 36x - 4 - 36x + 4#

#17x^2 - 36x + 4 = 0#

Factoring the quadratic gives:

#(17x - 2)(x - 2) = 0#

Solving each term for #0# gives:

#17x - 2 = 0#

#17x - 2 + 2 = 0 + 2#

#17x = 2#

#(17x)/17 = 2/17#

#x = 2/17#

and

#x - 2 = 0#

#x - 2 + 2 = 0 + 2#

#x = 2#