Using a quadratic formula to find the zeros of the function round to tenth if necessary y equals x squared - 21

Y = x^2 - 21
The roots occur when y = 0
x^2 - 21 = 0 Add 21 to both sides.
x^2 = 21     Take the square root of both sides.
sqrt(x^2) = sqrt(21)
x = +/-  4.583

I've enclosed a graph to make sure that you can see what the answer means.

Answer for 2: his profit would be $2.88 explanation: you have to first multiply 72 and 0.12 together to get $8.64 once you do that you know how much money the shopkeeper made from selling the candy bars individually. so you have to do 8.64-5.76=2.88 hope that ; )answer for 3: yeah i’m sorry i have no idea what number 3 is. i’m sorry i couldn’t with that.