Is this an appropriate assumption...

mateomy

[tex]
\frac{d^2}{dx^2}\,\int_{0}^{x}\Bigg(\int_{1}^{sint}\,\sqrt{1+u^4}\,du\B igg)\,dt
[/tex]






When solving something like this is it appropriate to look at it (for sake of ease), as just replacing [itex]u^4[/itex] with [itex]\sin{t}[/itex] then multiplying the original expression by the derivative of [itex]\sin{t}[/itex]?

mateomy

That upper bound is sint (dont know why it wont show up).
and thats replacing u^4 with sint and the derivative of sint.

fzero

What you're saying sounds vaguely like something you will need to do when you solve the problem correctly. You want to use the fundamental theorem of calculus (twice actually) first. The second time you will also need to use the chain rule, which is what you seem to be trying to say in other words. It's best to actually use the rules here to take the derivatives rather than try to guess at how things will fit together.

mateomy

Yeah, Fundamental Theorem....exactly what I (wasn't) saying, haha. Thanks. Just clarifying things in my own head; finals in 2 weeks. Thank you for confirming.