Quick Notation Question

[Guest]

im doing simpsons/trapezoidal methods etc. And it says find the area below the curve f(x)= x^3-2x

That just means integral (x^3-2x)dx right?

 

[galactus]

They probably want you to use Simpson's Rule or the trapezoid rule.

Did they give you the limits and the number of subintervals to use?.

 

[pka]

im doing simpsons/trapezoidal methods etc. And it says find the area below the curve f(x)= x^3-2x. That just means integral (x^3-2x)dx right?

The answer really depends on the interval. Area is found by integrals of non-negative functions. From sqrt(2) on this function is positive. So yes, on say [2,5] use Simpsons/trapezoidal methods to find area. But on say [0,5] care must be taken.

 

[Guest]

oh, i know how to use the rules i just wanted to verify that area under the curve of f(x) referred to integral of f(x)

 

[Guest]

so its juts S (x^3-2x)dx, right? I can use the formula i just want to verify this step.

 

[pka]

so its juts S (x^3-2x)dx, right? I can use the formula i just want to verify this step.

No, that is not correct! It depends upon the interval of integration.
Do you read the replies you receive?
To find area the function must be non-negative.