Finding area between 2 functions

In summary, the conversation discusses finding the area between two functions and their intersection points. The process involves finding the points of intersection, determining the greater function, and setting up and solving an integral. However, there is a mistake in the calculation of the integral and the correct answer is $\frac{16\sqrt{2}}{3}$.
  • #1
tmt1
234
0
1.

I have to find the area between

$x = 2y^2$
and
$x = 1 - y$

I find the intersection points

$ 1 -y = 2y^2$

$2y^2 + y - 1= 0 $

$(2y - 1)(y + 1)= 0$

so y = 1 and -1

However, x = y - 1 is not a vertical line so I am not sure how 1 and -1 can be intersections. Also, when I plug these numbers into the original equation they don't equate, so what am I doing wrong here?

1. I have another problem for finding the area between

$x = 2 - y^2$

and
$x = y^2 - 2$

I found that the points of intersection are y =$ +/- \sqrt{2}$ and the greater function is $ x = 2 - y^2$ so

$\int_{-\sqrt{2}}^{\sqrt{2}} 4 - 2y^2 \,d$

then

$\left[4y - \frac{2y^3}{3}]\right]_1^3$

and

$[4\sqrt{2} - \frac{2\sqrt{8}}{3}] - [- 4 \sqrt{2} + \frac{4 \sqrt{8}}{3}]$

and then

$4\sqrt{2}$

However the answer is $\frac{16\sqrt{2}}{3}$
 
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  • #2
tmt said:
1.

I have to find the area between

$x = 2y^2$
and
$x = 1 - y$

I find the intersection points

$ 1 -y = 2y^2$

$2y^2 + y - 1= 0 $

$(2y - 1)(y + 1)= 0$

Correct up to here. Now notice that $\displaystyle \begin{align*} 2y - 1 = 0 \implies 2y = 1 \implies y = \frac{1}{2} \end{align*}$. The other solution y = -1 is fine...
 

FAQ: Finding area between 2 functions

What is the definition of "finding area between 2 functions"?

Finding area between 2 functions refers to the process of calculating the total area enclosed by two curves on a graph. This is typically done by finding the points of intersection between the two functions and using integration to calculate the area under the curve between these points.

Why is finding the area between 2 functions important?

Finding the area between 2 functions is important in many real-world applications, such as in engineering, physics, and economics. It allows us to calculate the total amount of a quantity, such as volume or revenue, that is enclosed by two changing variables represented by the functions.

What is the difference between finding area between 2 functions and finding the area under a single function?

Finding the area between 2 functions involves calculating the area between two curves, while finding the area under a single function involves calculating the area under a single curve. The former is typically done using integration, while the latter can also be done using basic geometry formulas.

Can the area between 2 functions be negative?

Yes, the area between 2 functions can be negative. This occurs when the upper curve is below the lower curve, resulting in a negative value for the area. In this case, the area represents the difference in the values of the two functions at certain points.

Are there any limitations to finding the area between 2 functions?

The main limitation to finding the area between 2 functions is that it can only be done for functions that are continuous and differentiable. This means that there cannot be any abrupt changes or breaks in the curves, and they must have defined derivatives at all points.

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