document.write( "Question 999361: Very confused on taking antiderivatives. In my class I am not allowed to use integrals, just math logical to solve this problem: e^(x/5) + sin(3x). I know it's sort of like figuring out what the function must have been before the derivative was taken but this keeps giving me trouble. I have to reverse the derivative and get it back to its original state. sin(3x) is simple enough for it to be +sin(3x) it must be a negative cosine and something for which cancels the 3 out so 1/3 therefore, -1/3cos(3x) would be the original. But the original of e^(x/5) this one baffles me. It's really the (x/5) that I don't get. How does undoing that work exactly? what must I do/understand first before getting its antiderivative/\r
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Algebra.Com's Answer #617035 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
f'(x) = e^(x/5)dx
\n" ); document.write( "Find f(x)
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\n" ); document.write( "Let x/5 = u
\n" ); document.write( "Then du = (1/5)dx
\n" ); document.write( "dx = 5du
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\n" ); document.write( "dy = e^u(5du)
\n" ); document.write( "---
\n" ); document.write( "dy = 5e^u du
\n" ); document.write( "--
\n" ); document.write( "Integrate to get:
\n" ); document.write( "y = 5e^u
\n" ); document.write( "---
\n" ); document.write( "Substitute to get:
\n" ); document.write( "y = 5e^(x/5)
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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