Homework Help: Calculus

Posted by anon on Saturday, March 12, 2011 at 7:09pm.

1.evaluate (integral sign)x cos 3x dx
A.1/6 x^2 sin 3x + C
B.1/3 x sin 3x -1/2 sin 3x +C
C.1/3 x sin 3x +1/9 cos 3x +C << my choice.
D. 1/2 x^2 +1/18 sin^2 3x +C

2.evaluate (integral sign)xe(power of 2x)dx
A.1/6 x^2 e(to the power of 3x)+C

B.1/2 xe(to the power of 2x)-1/2 e(to
the power of 2x)+C

C.1/2xe(to the power of 2x) -1/4 e(to the power of 2x) +C

D.1/2 x^2 -1/8 e(to the power of 4x +C

I don't know the answer to this one.

Calculus - MathMate, Saturday, March 12, 2011 at 7:30pm
1. C is Correct
Integration by parts,
∫xcos(3x)dx
=(1/3)xsin(3x)-(1/3)∫cos(3x)dx
= ....

2. Same as 1. Use integration by parts

∫xe^2xdx
=(1/2)xe^2x-(1/2)∫e^2xdx
=...
Calculus - Anon, Sunday, March 13, 2011 at 5:30am
C ?
Calculus - MathMate, Sunday, March 13, 2011 at 9:50am
Perfect!

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