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Mathematics 8 Online
OpenStudy (anonymous):

Help please :)

OpenStudy (anonymous):

hartnn (hartnn):

is this calculus question?

OpenStudy (anonymous):

I would assume you differentiate... I assume you know calculus?

OpenStudy (anonymous):

If you can differentiate this becomes a lot easier to solve.

OpenStudy (anonymous):

No, sadly i don't ( ._.)

OpenStudy (anonymous):

Okay. Go to your calculator. Graph the function.

OpenStudy (anonymous):

you dont need to differentiate...just find the two roots of the equation (the places where t=0) and divide their sum by 2 to get the t coordinate of the highest point. then plug t into the equation to get the height

hartnn (hartnn):

there is a formula which gives vertex of a quadratic function, do u know that formula?

OpenStudy (anonymous):

Do you have a graphing calculator?

OpenStudy (anonymous):

@hartnn . THat's a lot harder >.< .

OpenStudy (anonymous):

But Hartnn is correct you can compete the square.

OpenStudy (anonymous):

@etemplin . Very clever. It works but I would have never thought of that.

OpenStudy (anonymous):

*confused* o:

OpenStudy (anonymous):

you can use calc or use the vertex equation, -b/2a using calc: s'= -32t+128 = 0 -32t = -128 t = 4 seconds using vertex equation -128/2(-16) = -128/-32 t= 4seconds

OpenStudy (anonymous):

the x coordinate is (-b)/(2a) of the vertex of a parabola. plug in the answer for this to get the y value

OpenStudy (anonymous):

She can't use calculus.

OpenStudy (anonymous):

he provided 2 ways...@emily9102 use the second way of @jayz657's post

OpenStudy (anonymous):

Ohh I know :P .

OpenStudy (anonymous):

I like the third way more.

OpenStudy (anonymous):

the formula (-b)/(2a) is the easiest

OpenStudy (anonymous):

By definition, the maximum point occurs halfway between the two solutions. (ie the vertex)

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

Wait. That's wrong.

OpenStudy (anonymous):

Ignore that.

OpenStudy (anonymous):

My mistake.

OpenStudy (anonymous):

For a quadratic of the form y=ax^2 + bx + c, the vertex occurs at x = -b/2a.

OpenStudy (anonymous):

Simple algebra error hehe...

OpenStudy (anonymous):

|dw:1351403737520:dw|

OpenStudy (anonymous):

So the maximum point occurs at x=4.

OpenStudy (anonymous):

|dw:1351403771244:dw|

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