Online Course Discussion Forum

Math Challenge I-C Handout 4

 
 
Picture of Wanyang Zhou
Math Challenge I-C Handout 4
by Wanyang Zhou - Friday, 6 October 2017, 11:16 AM
 

I don't understand 4.30. Can anyone help me?

Question 4.30:

Dylan dives from a platform that is 4040 feet high. Dylans mom wants to take a picture right when Dylan is at the same heigh as her. Dylan's height above the water after tt seconds is h(t)=16t2+8t+40h(t)=−16t2+8t+40. If Dylan's mom is sitting 1010feet above the water, how much time will pass before his mom takes the picture?


 
Picture of Wanyang Zhou
Re: Math Challenge I-C Handout 4
by Wanyang Zhou - Friday, 6 October 2017, 2:00 PM
 

Can anyone at least give me a hint?

Picture of Areteem Professor
Re: Math Challenge I-C Handout 4
by Areteem Professor - Friday, 6 October 2017, 3:05 PM
 

The problem gives us an equation for Dylan's height at time $t$:  $h(t)=−16t^2+8t+40$ (measured in feet). We know that Dylan's mom wants to take a picture when his height is $10$ feet (because that is the height she is sitting). Therefore we should be able to use the equation to determine when Dylan is at $10$ feet.

Hope this helps!

Picture of Wanyang Zhou
Re: Math Challenge I-C Handout 4
by Wanyang Zhou - Friday, 6 October 2017, 7:50 PM
 

Thank you  :)