Pre-Calc :
How do you get the direct relationship between y and x and how do you know if the parametric equations determine y as a function of x with the following?

x = 2t and y = 3t -1

Question

Pre-Calc :
How do you get the direct relationship between y and x and how do you know if the parametric equations determine y as a function of x with the following?

x = 2t and y = 3t -1

anonymous · Answer

y=1.5x since x=2t and y=3t-1 has 1.5 x's.

anonymous · Answer

OOPS! y=1.5x-1

anonymous · Answer

a direct relationship between y and x means that y = kx. this also is equivalent to saying that y varies directly as x , y is proportional to x, and that the graph of y goes through the origin and is linear . 
for your second question, solve for t,

anonymous · Answer

x = 2t, so t = x/2, now plug that into y,  y = 3 ( x/2) -1. 
is y now a function of x?

anonymous · Answer

a direct relationship between y and x means that y = kx for some k not zero, a constant k

anonymous · Answer

Thank you so much! I had trouble understanding this in school.

anonymous · Answer

its a special linear function, y = kx , where the y intercept is zero (passes through (0,0)