Question

A model rocket is launched from a roof into a large field. The path of the rocket can be modeled by the equation y = 0.04x+ 8.3x + 4.3, where x is the horizontal distance, in meters, from the starting point on the roof and y is the height, in meters, of the rocket above the ground. How far horizontally from its starting point will the rocket land?

Answer 1

208.02 m
416.03 m
0.52 m
208.19 m

Answer 2

@qudrex I think the equation is
\[y=0.04x^2+8.3x+4.3\]
??

Answer 3

your equation does not look correct, I think it should be:\[y = 0.04x^2+ 8.3x + 4.3\]

Answer 4

that is what it should be. it didnt copy over right.

Answer 5

@qudrex this is an equation of a parabola, Can you plot its graph?

Answer 6

no, the only thing i know is that's the thing they gave me with those multiple choices

Answer 7

Do you know Parabolas?

Answer 8

no idea what that is. :/

Answer 9

remember y represents the height of the rocket from the ground.
so when the rocket hits the ground, what will its height from the ground be equal to?

Answer 10

i got 12.6 but thats not one of the choices.

Answer 11

forget the answers.

when the rocket hits the ground, what will its height from the ground be equal to?

Answer 12

remember - it has "hit" the ground. so it is "on" the ground.

so what will its height be from the ground?

Answer 13

if it was on the ground it would have no height.

Answer 14

exactly, so it would be zero

Answer 15

so now we know when it hits the ground, y=0

Answer 16

so what you need to do is to set y=0 and solve the equation:\[0 = 0.04x^2+ 8.3x + 4.3\]

Answer 17

that will give you two possible answers for the horizontal distance (x). only one of which will be a valid answer.

Answer 18

do you know how to solve such equations?

Answer 19

i dont think so. im horrible with math.

Answer 20

in which case I suggest you first review that topic.

here is good site: http://www.mathsisfun.com/algebra/quadratic-equation.html