Question

Can someone please check the attached problems?

Answer 1

why yes, I would be happy to :)

Answer 2

3b), did you just use negative -500 mg for I(t)?

Answer 3

yes, it needs to have been 500 = -3t^2 + 126t

Answer 4

try quadratic formula again with 0 = -3t^2 + 126t - 500

Answer 5

I'm lost.

Answer 6

http://www.wolframalpha.com/input/?i=500+%3D+-3t^2%2B126t

Ibuprofen level starts at zero, take a pill, levels increase past 500, peak, and drop back below 500. The points the quadratic formula produces are the t values that go with the I(t) levels of 500

Answer 7

Start your set up by saying I(t) = Ibuprofen level at time t after taking pill.

I(t) = -3t^2 + 126t

when is I(t) = 500?

I(t) = 500 = -3t^2 + 126t
0 = -3t^2 + 126t - 500
then use quadratic formula.

Result is 2 t values which are possible times after taking pill before I(t) level of ibuprofen is equal to 500.

The problem asks for the longest time, so you would need to select the larger t value.

Answer 8

consolation prize... you had part (a) correct :)

Answer 9

So 3(a) is correct and I have to fix 3(b)?

Answer 10

I think prob 4 is right too.

Answer 11

ugh bad laptop!

Yes, 3b needs fixing, but you were close... just set up I(t) = 500, put in the expression for I(t), subtract 500 from both sides to get -3t^2 +126t - 500 = 0, and then use quadratic formula

Answer 12

Okay, thank you!

Answer 13

you just jumped into it too fast and put the 500 on the wrong side.

Answer 14

Always glad to help... I am really really really really really love the fact that you try these problems first and then post them for us to talk through... that is how this site is SUPPOSED to work!!

Answer 15

Now I have to get going though :) see you next time :)

Answer 16

See you next time :) Thank you so much :)