Don't definite Integrals find area?

lLovePhysics
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I'm confused here.. My definite integral doesn't match by Riemman Sum... and it should right? I think that I have not integrated correctly. Can someone help me spot the problem? Thanks.

Find the Area of the region bounded by:
f(x)=5-x^2 , [-2, 1]

Using the Riemma Sum idea (limit of the sum of rectangles as the number of rectangles approaches infinity), I got 12 units^2 as my area, which is correct.

However, using definite integrals and the Fundamental Theorem of Calculus, I get:

\int_{-2}^{1} (5-x^2)dx}

=-\frac{x^3}{3}\biggl] ^{1}_{-2}

Which equals -3 ?
 
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5x - 1\3 * x^3
 
rocophysics said:
5x - 1\3 * x^3

Noooo.. I can't believe I made another stupid mistake! Thanks Roco
 
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