# Thread: Teacher cant even do this.......

1. ## 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

2. Title: Teacher cant even do this.......
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 $\left| \int_{-1}^{1} 2(x^2 - 1) \, dx \right| = 2 \left| \int_{-1}^{1} x^2 - 1 \, dx \right|$.

I assume you know how to integrate (otherwise this question is pointless).

3. 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

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

I've got $a = \frac83$