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Find the parametric equations of a line that passed through point (2,-9) and has slope -3/4. Assume t = 0 corresponds to the given point, t increases as x increases, and that the speed is sqrt(25).

x(t) =

y(t) =

difficulty advanced
 Jun 4, 2015

Best Answer 

 #1
avatar+130516 
+5

Since the starting point is (-2, 9), the slope is -3/4, and t increases as x increases,  we have....

x(t) = -2 + 3t

 

y(t)  = 9 - 4t

 

Notice that when t = 1, x = 1 and y = 5

 

And the distance between the ponts is  √[(-2 -1)^2 + (9 - 5)^2] = √[3^2 + 4^2] = √25......which means that some object traveling on this line starting at (-2,9) and moving at this speed (per some time unit) will reach (1, 5)  after one of these time units.....just what we want....!!!

 

 

 Jun 4, 2015
 #1
avatar+130516 
+5
Best Answer

Since the starting point is (-2, 9), the slope is -3/4, and t increases as x increases,  we have....

x(t) = -2 + 3t

 

y(t)  = 9 - 4t

 

Notice that when t = 1, x = 1 and y = 5

 

And the distance between the ponts is  √[(-2 -1)^2 + (9 - 5)^2] = √[3^2 + 4^2] = √25......which means that some object traveling on this line starting at (-2,9) and moving at this speed (per some time unit) will reach (1, 5)  after one of these time units.....just what we want....!!!

 

 

CPhill Jun 4, 2015

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