Silly Questions Thread

[lachymm]

What is the general solution to ?
I got from the calc but it isnt the right answer

[lachymm]

Thanks matty, i think i will leave it to last if its on the exam because i seem to always struggle with time in the second one..

[brightsky]

2tan(x) + 1 = 3
2tan(x) = 2
tan(x) = 1
Base angle: pi/4
Some of the other angles: pi + pi/4, 2p + pi/4, 3p +pi/4,...
So the general solution is npi + pi/4 = (4npi + pi)/4 = pi(4n + 1)/4, where n is an integer.

[jasoN-]

[m@tty]

What is the general solution to ?
I got from the calc but it isnt the right answer

That is a correct alternate form.

That takes as the base angle.

So the general solution is

[lachymm]

Thanks bright sky. how come my calculator gives me the wrong answer?..also how do you remember that = 1? because none of the triangles have 90 degree angle on them that you can solve for tan?

[brightsky]

I usually remember tan through sin and cos (probably not the best way to remember it). So sin(pi/4) = cos(pi/4) so tan(pi/4) = sin(pi/4)/cos(pi/4) = 1.

[lachymm]

Oh cheers, matty bet my question. Do you need to recognize that is the same as ? geez the exam writers are shifty

[lachymm]

When i derive the calculator gives me what does this mean?
Or do i need to set the domains of 2 different functions then derive individually?

[m@tty]

Oh cheers, matty bet my question. Do you need to recognize that is the same as ? geez the exam writers are shifty

So that's why it works.

[brightsky]

When i derive the calculator gives me what does this mean?
Or do i need to set the domains of 2 different functions then derive individually?

See signum function. 5sgn(5x + 3) = 5(5x+3)/(|5x + 3|). For methods, it's probably better to just split it into cases.

EDIT: Mogz, thanks m@tty. Again. :p

[lachymm]

thanks how do i go about finding when the derivitive of is not defined?
I know you cant get the log of a negative number or 0. But i got the general solution of and its nothing like the answer btw i got for the general solution courtesy of the calc

[lachymm]

When i derive the calculator gives me what does this mean?
Or do i need to set the domains of 2 different functions then derive individually?

See signum function. 5sgn(5x + 3) = 5|x|/(x(5x + 3)). For methods, it's probably better to just split it into cases.

thanks brightsky

[m@tty]

When i derive the calculator gives me what does this mean?
Or do i need to set the domains of 2 different functions then derive individually?

When you differentiate a modulus function you should split it into its components.

It makes it much easier.






The same thing is given by

The signum operation takes only the sign (+ or -) of the number, so if then and so the derivative is -5. Similarly for the derivative is 5.

[brightsky]

sin(2x) = 0
2x = 0, pi, 2pi, 3pi, etc.
So yes your answer is correct.