Subtract seven more than twice a number from the square of one-third of the number you get zero

We will first translate this word problem into numerical expression.
Subtract seven more than twice a number from the square of one-third of the number and you get zero can be written into this form;
Let x = number






Therefore, the value of x are
 x - 21 = 0           and            x + 3 = 0
        x = 21                                  x = -3

{21, -3}

There is no graph but what i can say is that 1 is the slope and that -2 is the y- intercept