Frustrating Math Problem!

by **Warren** » May 8, 2004 @ 10:26pm

Our TI calculators can't do indefinite integrals, only definite (and that's an approximate too). Of course we do integrals by hands, but not insanity arctangent ones...

To that Pure 3 question:
x(x^2 - 9)^-1 dx = ln(x^2 - 9)/2 + c
That's an easy one, but can anyone do cos(x^2)dx? We never completely learned how to do that.

by **Jadam** » May 8, 2004 @ 11:54pm

by **RChickenMan** » May 9, 2004 @ 2:42am

by **David Horn** » May 9, 2004 @ 1:26pm

Hmm... I'm sure I saw one doing one. Maybe it was a differentiation. You'd put in the equation you were starting with and it would spit out the differential.

cos(x^2).dx? You need to rewrite it using a trigonometric identity in order to integrate.

cos(x^2) = 1/2(1+cos(2x) (which can be integrated)

1/2[1 + cos(2x) => 1/4(2x + sin(2x)) + c => 1/4sin(2x) + 1/2x + c

by **damian** » May 9, 2004 @ 1:28pm

by **David Horn** » May 9, 2004 @ 5:28pm

by **damian** » May 9, 2004 @ 5:28pm

by **Caesar** » May 9, 2004 @ 6:04pm

by **James S** » May 9, 2004 @ 7:33pm

by **David Horn** » May 10, 2004 @ 11:14am

by **James S** » May 10, 2004 @ 3:26pm

cos (3^2) = -.91113026
(cos 3)^2 = 0.9800851

You're wrong, David, and so is your math teacher. They're two different things.

Frustrating Math Problem!

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