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Homework Statement
y=1 / (cos h x), find dy/dx
Homework Equations
chain rule and coshx=(e^x+e^-x)/2
What an idiot I am. This mistake is proof that I am tired and should get some sleep. Well what other method do you suggest I use, I'd definitely like to know if it's more efficient.Resize your image!!! Way too big.
The most obvious error is ##\frac{dy}{du} = \ln |u|##. Sure that's the derivative, and not the integral?
Other than that, for Chain Rule, it's generally not helpful to substitute variables like this. Not wrong, but it can overcomplicate things.
I've already solved it.Start with the definition of cosh(x) in terms of the exponentials and re-write 1/cosh(x). What is dy/dx when y = 1/x or x^-1?
Essentially what you did, but you don't have to spell out every step explicitly.What an idiot I am. This mistake is proof that I am tired and should get some sleep. Well what other method do you suggest I use, I'd definitely like to know if it's more efficient.
Yes, I know how to resize images - which is how I viewed yours. The problem is that it becomes impossible to view your text (and mine, when I post) in the same sizing. The font becomes too small.You can resize my image by clicking Ctrl and - on the keyboard. If you have a mouse with a wheel then turn the wheel towards you (downwards) while holding down Ctrl