Calculus question- differentiation

AI Thread Summary
The discussion revolves around finding the derivative dy/dx for the function y = (5e^(2+ix))/(3e^(1-2ix)). The user initially applies the quotient rule but struggles with simplification. After some back-and-forth, they successfully simplify the expression to y = (5/3)e^(1 + 3ix). The final derivative is determined to be dy/dx = 5ie^(1 + 3ix). The conversation concludes with the user expressing satisfaction with the resolution of their question.
tracey163
Messages
3
Reaction score
0
Could someone please help me with the method and steps to this question:

Find dy/dx for the following:

y = (5e^(2+ix))/(3e^(1-2ix))
 
Physics news on Phys.org
Simplify it so it is of the form constant*e^(something) and then carry out differentiation of exponentials as you would.
 
This is the way I tried to do it:

(Quotient rule)
dy/dx = ((5ie^(2 + ix))(3e^(1-2x)) - (-6ie^(1 - 2ix))(5e^(2 + ix))) / ((3e^(1 - 2ix))^2)

= (15ie^(3 - ix) + 30ie^(3 - ix)) / (9(e^(1 - 2ix))^2)

= (45ie^(3 - ix)) / (9(e^91 - 2ix)^2)

= (5ie^(3 - ix)) / ((e^(1 - 2ix))^2)

And I'm not sure where to go from there its either wrong or it needs simplifying some more...
 
Ah thanks, yeah your right, I've got it :) it all makes perfect sense now :)

y = 5/3.e^(2 + ix - (1 - 2ix))

=5/3.e^(1 + 3ix)

dy/dx = 5ie^(1 + 3ix)

:D thanks!
 
You're welcome :-)
 
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...

Similar threads

Back
Top