# Teacher cant even do this.......

• Mar 31st 2008, 04:21 AM
eftheking
Teacher cant even do this.......
Find the area enclosed by the x-axis and the curve y=2(x squared-1).

would be grateful if u could do it all as i have no idea.
Thank u
• Mar 31st 2008, 04:37 AM
mr fantastic
Title: Teacher cant even do this.......
Quote:

Originally Posted by eftheking
Find the area enclosed by the x-axis and the curve y=2(x squared-1).

would be grateful if u could do it all as i have no idea.
Thank u

Personally, I dislike melodramatic titles for a question. Especially when it stretches ones credulity. I'd be absolutely astonished if your teacher can't do this. So please, do not insult your teacher in this manner.

The answer is $\displaystyle \left| \int_{-1}^{1} 2(x^2 - 1) \, dx \right| = 2 \left| \int_{-1}^{1} x^2 - 1 \, dx \right|$.

I assume you know how to integrate (otherwise this question is pointless).
• Mar 31st 2008, 04:43 AM
earboth
Quote:

Originally Posted by eftheking
Find the area enclosed by the x-axis and the curve y=2(x squared-1).

would be grateful if u could do it all as i have no idea.
Thank u

1. Calculate the zeros of the function. There are 2 zeros. (a, b)

2. The enclosed area is

$\displaystyle a = \left|\int_a^b(2x^2-2)dx\right|$

I've got $\displaystyle a = \frac83$