Hyperbolic functions..
\(\large y= c_1 \sinh (kx) + c_2 \cosh (kx) \)
take the derivative, wat do u get ?
use below : (sinhx)' = coshx (coshx)' = sinhx
okay, the derivative of sinh is cosh and derivative of cosh is -sinh..
derivative of cosh is just sinh
there is no negative sign
\(\large y= c_1 \sinh (kx) + c_2 \cosh (kx)\) take derivative \(\large y'= c_1 \cosh (kx)(k) + c_2 \sinh (kx)(k)\) \(\large ~~~= c_1k \cosh (kx) + c_2k \sinh (kx)\)
take derivative again
you wud get : \(\large y'= c_1k \cosh (kx) + c_2k \sinh (kx)\) \(\large y''= c_1k \sinh (kx)(k) + c_2k \cosh (kx)(k)\) \(\large ~~~~= c_1k^2 \sinh (kx) + c_2k^2 \cosh (kx)\) \(\large ~~~~= k^2\left(c_1\sinh (kx) + c_2 \cosh (kx)\right)\)
the thing inside parenthesis should look familiar ?b
well, i thought the derivative of cos is -sin
im sorry but imma little bit confused.. but.. how do i take the derivative after this? im sorry
derivative of \(\cos(x)\) is \(-\sin (x)\) derivative of \(\cosh(x)\) is \(\sinh (x)\)
yes.. they're correct and what's after this? =)
What's \(\large k^2 y =\color{red}?\)
stare at last line
\(\large ~~~~= k^2\left(c_1\sinh (kx) + c_2 \cosh (kx)\right)\)
the thing inside parenthesis is exactly same as ur given function \(y\) right ?
we're done actually :)
just replace the entire thing inside parenthesis wid "y"
\(\large y'' ~~~~= k^2\left(c_1\sinh (kx) + c_2 \cosh (kx)\right)\) \(\large y'' ~~~~= k^2\left(y\right)\)
slap that right hand side stuff to left side
\(\large y'' - k^2\left(y\right) = 0\)
Thank you so much!!!!!!!!!!!! =)
let me knw if smthng doesnt make sense :)
u wlc ! :)
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