Question

The equation y=x^2-12x+45 models the number of books y sold in a bookstore x days after an award-winning author appeared at an autograph-signing reception.

How many books were sold at the autograph session?

What is the minimum nunber of books sold?

What day did that occur?

How many books were sold on day fifteen?​

Answer 1

Answer: The first day the author reaches 100 days is on day 16.

To solve this problem, you could use a graphing calculator to graph the given equation. Then, determine when this line crosses 100. It crosses when x = 15.539. Therefore, we would have to round up to 16 so it is at least 100.

You could use the quadratic equation to solve: 100 = x^2 -12x + 45

Either you will get 16. If you use the quadratic formula, make sure to only use the positive answer.

Answer 2

3.2

Explanation: