Area between a parabola and line?

In summary, the area of the region enclosed by the given curves can be found by breaking it up into vertical or horizontal strips and using one or two integrals, depending on the method chosen. The equations used for the integrals are y = sqrt(x) and y = (7-3x)/2.
  • #1
smandphysics
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Homework Statement



Find the area of the region enclosed by the curves:
2y=sqrt(4x)
y=5 and
2y+3x=7

Homework Equations


A = integral from a to b of f(x)-g(x) dx


The Attempt at a Solution



Tried to integrate this with respect to y.
Found the intersection points to be y=2, -14/3
Then did the integral from -14/3 to 2 of (7/3 - 2y/3) - (1/4y^2)
My answer was 1000/81 but this is incorrect.
Also tried integral from -14/3 to 5 of (7/3 - 2y/3) - (1/4y^2)./
My answer was 841/324 but this was also incorrect.

Thanks to anyone who can help explain this to me, I'm so lost :s
 
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  • #2
I would recommend you graph all those functions to give you an idea of where all the intersections are. For example y=(7-3x)/2 intersects y=5 in one place. Similarly y=(sqrt4x)/2 intersects y=5 in one place. And y=(7-3x)/2 and y=(sqrt4x)/2 intersect each other in one place. Your job is to sort out which integral to subtract from which to get at the area between all three functions. Hope this helps.
 
  • #3
In addition to what armolinasf said, the equation 2y = sqrt(4x) can be simplified to y = sqrt(x).

If you break up the region into vertical strips, you will need to use two integrals. If you break the region up into horizontal strips, you'll need only one integral.
 

FAQ: Area between a parabola and line?

1. What is the formula for finding the area between a parabola and a line?

The formula for finding the area between a parabola and a line is ∫(f(x) - g(x)) dx, where f(x) is the parabola and g(x) is the line.

2. How do you determine the limits of integration for finding the area between a parabola and a line?

The limits of integration can be determined by finding the points of intersection between the parabola and the line. These points will be the lower and upper limits of integration.

3. Can the area between a parabola and a line be negative?

Yes, the area between a parabola and a line can be negative if the parabola lies below the line. In this case, the integral will result in a negative value.

4. Is it possible for the area between a parabola and a line to be infinite?

No, the area between a parabola and a line is always finite, as long as the limits of integration are finite. However, the area can approach infinity if the limits of integration are infinite.

5. Can the area between a parabola and a line be calculated using basic geometry instead of integration?

Yes, the area between a parabola and a line can also be calculated using basic geometry by finding the points of intersection and using the formula for the area of a trapezoid (1/2 x (base1 + base2) x height).

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