Expert: Ahmed Salami - 2/10/2010

Question
1) Directions: Express in the form y=f(x) by eliminating the parameter.

1)x=e^-2t , y=6e^4t


2) Directions: Find parametric equations for the given curve.

2) x^2 + y^2 = 49

Answer
Hi Nicole,
1) x = e^-2t
We can see that
x^(-2) = (e^-2t)^(-2)
x^(-2) = e^[(-2t)(-2)]
x^(-2) = e^(4t)
y = 6e^(4t)
So,
y = 6x^(-2)

2) x^2 + y^2 = 49
x^2 + y^2 = 7^2
This represents the equation of a circle with center at the origin and with radius 7. The parametric equations are written as
x = 7cost
y = 7sint

Regards