Question

5x/4 - x/2 - 9/6 = 9/2

Answer 1

Reduza todo o lado esquerdo a um mesmo denominador (mmc):

$\begin{array}{l}\mathsf{\dfrac{5x}{4}-\dfrac{x}{2}-\dfrac{9}{6}=\dfrac{9}{2}}\\\\\\\mathsf{\dfrac{15x}{12}-\dfrac{6x}{12}-\dfrac{18}{12}=\dfrac{9}{2}}\end{array}$

Agora multiplique todos os termos (de ambos os lados da igualdade) por 12 com intuito de cancelar os denominadores do lado esquerdo:

$\begin{array}{l}\mathsf{12\hspace{-9}\diagup\cdot\begin{pmatrix}\mathsf{\dfrac{15x}{12\hspace{-9}\diagup}-\dfrac{6x}{12\hspace{-9}\diagup}-\dfrac{18}{12\hspace{-9}\diagup}}\end{pmatrix}=12\cdot\dfrac{9}{2}}\\\\\\\mathsf{15x-6x-18=\dfrac{108}{2}}\\\\\\\mathsf{9x-18=54}\\\\\\\mathsf{9x=72}\\\\\\\mathsf{x=\dfrac{72}{9}}\\\\\\\mathsf{x=8}\end{array}$