Math help

[007agentHP]

hello, im trying to solve this math problem on my homework. the question is,

 

A diver follows a parabolic path modeled by the quadratic equation y = - 3x^2 + 9x + 28 when diving off of a high dive. how long until he reaches his maximum height? what is the maximum height?

 woud i just plug these suckers into the quadratic equation or would i do something different? bc i know 3 methods of solving. factoring, finishing the square, and formula.

[dmanschramm]

Lol going to the LTT forum for help.

 

For the x component of the vertex, it is -b/2a so in your case -(9)/2*-3

The x component is 1.5. Instead of x, replace it with 1.5

 

y=-3*2.25 + 9*1.5+28

 

y=48.28

 

The maximum height is 48.25 units off of the high dive, which occurs 1.5 units out

 

Hope this helps

 

 

-A fellow Grade 10 student

[Imabigmac]

Would the height just be the sart point or y min? A parabola will go on forever so... I could solve it on a graphing calculator or by graphing the equation but I forget how solve with algebra.

My logic is probably flawed, haven't done this in a few years.

[dmanschramm]

Would the height just be the sart point or y min? A parabola will go on forever so... I could solve it on a graphing calculator or by graphing the equation but I forget how solve with algebra.

 

The maximum height would occur at the vertex. The height is indicated by the y value, if that helps... y indicates vertical location (height), whereas x indicates horizontal location (distance from the dive point in this case)

[dmanschramm]

If there's anything that doesn't make sense, let me know

[Imabigmac]

The maximum height would occur at the vertex. The height is indicated by the y value, if that helps... y indicates vertical location (height), whereas x indicates horizontal location (distance from the dive point in this case)

at the vertex which would also be Y min , no?

[dmanschramm]

at the vertex which would also be Y min , no?

It's Y max in this case because the concavity of the quadratic is down... so it has a maximum...

[007agentHP]

Lol going to the LTT forum for help.

 

For the x component of the vertex, it is -b/2a so in your case -(9)/2*-3

The x component is 1.5. Instead of x, replace it with 1.5

 

y=-3*2.25 + 9*1.5+28

 

y=48.28

 

The maximum height is 48.25 units off of the high dive, which occurs 1.5 units out

 

Hope this helps

 

 

-A fellow Grade 10 student

thank you. if orgot about x = -b/2a i was trying the quadratic formula and i totally forgot about graphing

[Seefeldt951]

The max height would be at Y max. This is an upside down parabola.

[dmanschramm]

The max height would be at Y max. This is an upside down parabola.

 

Exactly ^^

[dmanschramm]

thank you. if orgot about x = -b/2a i was trying the quadratic formula and i totally forgot about graphing

 

Don't worry bout it... the LTT forum has got your back bro

[Tonylu1595]

Put it in a graphing calculator?