Estime number of items that need to be sold to make profit algebra

Question

The table below shows the profit, p(x), in dollars from selling x items

X 1 2 3 6 9 14

Y 90.6 106.4 112.4 71.6 -57.4 -468.4

Using your quadratic regression, estimate the number of items that need to be sold to make a profit of $-192.4 ?  _____ items

Answer 1

y≈ax²+bx+c

From the regression, a=-4.9, b=30.5 and c=65

Use quadratic formula to solve for x in -4.9x²+30.5x+65 = -192.4

I get ≈ 11 items