Some of the steps in the derivation of the quadratic formula are shown. step 4: step 5: step 6: step 7: which best explains why the expression cannot be rewritten as during the next step? negative values, like −4ac, do not have a square root. the ± symbol prevents the square root from being evaluated. the square root of terms separated by addition and subtraction cannot be calculated individually. the entire term b2 − 4ac must be divided by 2a before its square root can be determined.

The correct answer for this question is this one: "The square root of terms separated by addition and subtraction cannot be calculated individually."

The statement that best explains why the expression cannot be rewritten as during the next step is that the square root of terms separated by addition and subtraction cannot be calculated individually.
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As per my research the correct question is

A charity organization had a fundraiser where they sold each ticket for a fixed price. After selling 200 tickets, they had a net profit of $12,000. They had to sell a few tickets just to cover necessary production costs of $1,200.

Let y represent the net profit (in dollars) when they have sold x tickets.

Complete the equation for the relationship between the net profit and number of tickets sold.

This problem requires us to show the relationship between between net profit and ticket sold in the form of an equation.

Let y represent the net profit and x represent tickets sold , then

  y =  66 * x - 1200

Net profit is equal to sales - cost incurred. In problem total cost is given as 1200 dollars and it is fixed cost. It is also mention that by selling 200 ticket company makes profit of 12000 dollars.

So base on the data provided we can easily calculate sale price per ticket

i.e (12000+1200)/200 = 66