# Early introduction to calculus, for beginning-algebra students

#### sinx

##### Junior Member
A small marshmallow is launched straight up in the air with a slingshot. Its height h in meters, relative to te ground, is given by the function h(t) = 5 + 20 - 5t^2, where t is measured in seconds. About when does the marshmallow reach its maximum height?
hint; max ht is when velocity=0.
v=dh/dt.

and as said previous you are missing a t.
h(t) = 5 + 20t - 5t^2

#### HallsofIvy

##### Elite Member
Since this was posted in "beginning algebra", taking the derivative is probably not appropriate. Instead "complete the square".

#### sinx

##### Junior Member
Since this was posted in "beginning algebra", taking the derivative is probably not appropriate. Instead "complete the square".
i'm confused.
If you set h(t)=0 and solve for t, you will get two times when ht =0.

#### mmm4444bot

##### Super Moderator
Staff member
… max ht is when velocity=0 …

i'm confused … [there are] two times when ht =0.

I'm a bit confused, too. Is the second 'ht' above an abbreviation of h(t) ?

#### Denis

##### Senior Member
I'm a bit confused, too. Is the second 'ht' above an abbreviation of h(t) ?
"English is the most ambiguous language in the world." ~ Yours Truly, 2018!