# Math Help - differential equation (substitution)

1. ## differential equation (substitution)

for this question , i 've got my positive 9 but i got -64 , can anyone tell me which part is wrong?

Question : https://www.flickr.com/photos/123101...3/13907725466/
Wroking : https://www.flickr.com/photos/123101...n/photostream/

2. ## Re: differential equation (substitution)

When you take e to the $\ln \left| -\frac{64}{9} \right|$, you get $\frac{64}{9}$, not $-\frac{64}{9}$.

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