Question

The difference of the square of a number and 18 is equal to 3 times that number. Find the negative solution.

Answer 1

`x=number\hspace{5em}x^2=\textit{squared number} \\\\\\ \stackrel{\textit{difference of }x^2\textit{ and 18}}{x^2~~ - ~~18}~~ = ~~\stackrel{\textit{three times }x}{3x} \\\\\\ x^2-3x-18=0\implies (x-6)(x+3)=0\implies x= \begin{cases} 6\\\\ -3 ~~ \checkmark \end{cases}`