Finding a definite integral from other given definite integrals.

**bijosn** · April 10th 2011, 10:11 AM

What is this technique called?:

Suppose f is continuous and $\displaystyle \int_{-2}^{2}f(x)dx = 4$ and
$\displaystyle \int_{-2}^{5}g(x)dx = 2$

Determine $\displaystyle \int_{5}^{2}f(y)dy$

I am just doing this out of memory, tell me if its right
$\displaystyle \int_{5}^{2}f(y)dy = -(\int_{-2}^{5}g(x)dx) - (-(\int_{-2}^{2}f(x)dx))$
$\displaystyle \int_{5}^{2}f(y)dy = - 2 - (-4) = 2$

**TheCoffeeMachine** · April 10th 2011, 10:35 AM

I don't think it would have a name. It isn't that significant.

**bijosn** · April 11th 2011, 10:13 AM

no name? is my calculation atleast correct?

**mr fantastic** · April 11th 2011, 03:04 PM

Originally Posted by bijosn

no name? is my calculation atleast correct?

Assuming it's meant to be f and not g in the second given integral, your answer is correct. (If it was wrong the TheCoffeeMachine would have said so in his/her post, by the way).

**bijosn** · April 13th 2011, 02:08 AM

thank you, I apologize for not being sufficiently intuitive to understand the subtle ways of the coffee machine

Thread: Finding a definite integral from other given definite integrals.

LinkBack

Thread Tools

Display

Finding a definite integral from other given definite integrals.

Similar Math Help Forum Discussions

[SOLVED] Definite Integrals - Same Problem, 1st use Definite Integral, then FTC.

Finding a definite integral

definite integral....finding the function

finding f for a definite integral

finding the derivative of a definite integral

Search Tags