Three times a number x can be written as
[tex]3x[/tex]
The quotien between this and 2 is
[tex]\dfrac{3x}{2}[/tex]
from this, we will subtract something:
[tex]\dfrac{3x}{2}-\ldots[/tex]
And this "something" is three times the square of x. The square of x is [tex]x^2[/tex], and three times this is [tex]3x^2[/tex]
So, our final expression is
[tex]\dfrac{3x}{2}-3x^2[/tex]
