[tex]\frac{240}{x} = \frac{240}{x+3} + \frac{4(x+3)}{x + 3}[/tex]
[tex]\frac{240}{x} = \frac{240 + 4(x+3)}{x+3} [/tex]
( 240 )( x + 3 ) = 240x + 4x( x + 3 )
240x + 720 = 240x + [tex]4x^2[/tex] + 12x
[tex]4x^2 + 12x -720 = 0 [/tex]
dividimos entre 4
[tex]x^2 + 3x - 180 = 0 [/tex]
(x + 15) (x - 12) = 0
x = -15 ; x = 12
