Question

how do I know when trying to solve a quadractic equation and having to graph it, if it opens open or down on the graph?

Answer 1

if the term in x^2 has a positive coefficient then it opens up on the graph - if its negative it opens down

Answer 2

This is the equation -0.2x^2+12x+11=0

Answer 3

crudely speaking x^2 is like a U and -x^2 is like an upside down U !

Answer 4

ok thanks!!!!

Answer 5

micaiah graph would open down because of the -0.2x^2

Answer 6

Could you help me solve this? x=1on that same equation.

Answer 7

thats u of course!

Answer 8

oh - you want the points of intersection of the quadratic and x=-1 right?

Answer 9

Well let me explain the problem to you. Suppose you are an event coordinator. The box office manager wants a projected ticket sales report. The quadratic equation that I gave models the expected number of ticket sales for each day (x). (x=1 is the day the tickets go on sale)

Answer 10

On day one, sales projected = 0.2 + 11 + 12 = 23.2 - i suppose that becomes 23 as tickets sold must be whole numbers. Day 2 sales will be found by plugging in x=2 and so on

Answer 11

you can also find when the maximum number of sales occur by finding the vertex (peak) of the curve

Answer 12

this -b/2a for the function ax^2 + bx + c
for our quadratic it is
-12 / 2(-0.2) = 30 ie on 30th day

Answer 13

on that day number of sales = -0.2 *30^2 +12(30) + 11 tickets = 191

Answer 14

sorry - i calculated day one incorrectly - its -0.2 + 11+12 tickets = 22.8 - we can call that 23 tickets

Answer 15

30 days corresponds to the peak of the curve - after that day tickets sales will decrease

Answer 16

if u drew the graph you can read off the projected sales for any day. graph will look like a symmetrical arch. The math name for it is a parabola

Answer 17

good luck!

Answer 18

Thank youu so much. I really needed your help. I really appreciate it.