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Jamal is sledding down a 24m hill. Compared to when he's racing down the hill, he goes 6 m/s slower when he's pulling back up the hill. Sadly, this means he spends 9 more seconds pulling the sled back up than he does riding it down each time he takes a turn. 

 

What is his speed when he is riding down the hill?

 Dec 17, 2021
 #1
avatar+22572 
+2

Using the formula:  D  =  R · T

 

Downhill:  24  =  R · T

Uphill:       24  =  (R- 6) · (T + 9)     

 

Downhill:  24  =  R · T     --->     T  =  24 / R

 

Uphill:      24  =  (R- 6) · (T + 9)   

                      =  (R- 6) · (24/R + 9)                 

                      =  24 + 9R - 144/R - 54

                  0  =  9R - 144/R - 54

                  0  =  9R2 - 54R - 144

                  0  =  R2 - 6R - 16

                  0  =  (R - 8)(R + 2)

 

Rate =  8 m/s

 Dec 17, 2021

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