# Elimination Techniques

• Jul 23rd 2009, 02:49 PM
mvho
Elimination Techniques
Hey Guys, I am having troubles with the last 2 questions:

1. Eliminate t to give an equation that relates x and y:

$x=e^{2t}$ and $y=e^{7t}+5$

The main problem is, I don't quite understand what they are asking for. I THINK, you would solve for t and then plug in t for y?

Such as:
$ln(x)=2t$

So, I would plug this into Y to get:

$y=e^\frac{7}{2}ln(x)$

** That lnx should be in the exponent as well**

2.
Eliminate t to give an equation that relates x and y:
$x=tan(t), y=sec^2(t)-4$

Again, I applied the same principles as above and got this:

$sec^2*atan(x)-4$

Both answers are wrong but I don't see how else you can interpret these questions.

Confused.
• Jul 23rd 2009, 04:06 PM
skeeter
Quote:

Originally Posted by mvho
1. Eliminate t to give an equation that relates x and y:

hopefully these equations you attempted to post are correct ...

$x=e^{2t}$

$y=e^{7t}+5$

2.
Eliminate t to give an equation that relates x and y:

$x=\tan(t)$

$y=\sec^2(t)-4$

1. $y = (e^{2t})^\frac{7}{2} + 5$

$y = x^\frac{7}{2} + 5$

2. $y = (1 + \tan^2{t}) - 4$

$y = (1 + x^2) - 4$
• Jul 23rd 2009, 06:47 PM
mvho
Thanks skeeter. I can see how you solved the equation now.

I find the wording a little bit tricky.