4U Maths Question Thread

[RuiAce]

Hey guys whats the general solution to the following qs: (I put more than one coz they're pretty simple.. I think)

1) sin(x-pi/3) = cos2x

2) sin3x + sinx = 0

3) tan2x + cot3x =0

Also is the general solution for cosx = 0 , x= (2n+1)pi OR +/-pi/2 + 2npi ?

Thanks heaps for your help 

The former is wrong. Look again.
I think you forgot a /2.

Only the latter is correct. (For the cos)
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Hints for (i) and (ii):





I hope you do realise that practically 90% of the questions you've asked won't be on Friday. It's good seeing you tackle hard problems but I don't see the benefit of only doing these and not doing more recent and relevant past papers right now.

[massive]

thanks Rui, one more thing- can you quotes the formula for the chord of contact (in conics) or do you have to prove it?

[RuiAce]

thanks Rui, one more thing- can you quotes the formula for the chord of contact (in conics) or do you have to prove it?

Prove it. You only quote things that they give you in the exam.

[Brenda0708]

Hi, if you take the reciprocal of a function that has an oblique asymptote, what happens to the asymptoe? (HSC 2012 Q14bi) --> an oblique asymptote with equation y=2x-1 turned into an asymptote with equation y=0. How do you know? And is this the case for all oblique asymptotes? Thanks.

[RuiAce]

Hi, if you take the reciprocal of a function that has an oblique asymptote, what happens to the asymptoe? (HSC 2012 Q14bi) --> an oblique asymptote with equation y=2x-1 turned into an asymptote with equation y=0. How do you know? And is this the case for all oblique asymptotes? Thanks.

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If you can understand how things work, then it should be much more abundantly clear why f(x) having an oblique asymptote means that 1/f(x) has the horizontal asymptote y=0 (x-axis)
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[Brenda0708]

Oh my, thank you for your explanation. That makes so much more sense now ). Could you please give an example of what you meant with y=a and y=1/a? I'm trying to make sense of it but I think Im just confusing myself :')

[RuiAce]

Oh my, thank you for your explanation. That makes so much more sense now ). Could you please give an example of what you meant with y=a and y=1/a? I'm trying to make sense of it but I think Im just confusing myself :')

[Brenda0708]

Thank you!! 

[massive]

should we draw graphs and other diagrams in pen or pencil? I was just wondering because of the whole scanning process and them not being able to see your work unless its in black pen.

[RuiAce]

should we draw graphs and other diagrams in pen or pencil? I was just wondering because of the whole scanning process and them not being able to see your work unless its in black pen.

I drew all of my graphs in pen last year

[massive]

guys how do you do this... i can't seem to get the table of values right :/

[RuiAce]

guys how do you do this... i can't seem to get the table of values right :/

Show us your working

[massive]

Show us your working

I don't really have working, this is what i have for the seven ordinates:
0, pi/8, 3pi/8, pi/2, 5pi/8, 6pi/8, pi
The only problem is these aren't evenly spaced :/

[RuiAce]

I don't really have working, this is what i have for the seven ordinates:
0, pi/8, 3pi/8, pi/2, 5pi/8, 6pi/8, pi
The only problem is these aren't evenly spaced :/

7 evenly spaced coordinates just mean that there should be 6 equally-sized 'intervals' between the ordinates.

Hence, take x=...
0, π/6, 2π/6, 3π/6, 4π/6, 5π/6, 6π/6

i.e.
0, π/6, π/3, π/2, 2π/3, 5π/6, π

[massive]

7 evenly spaced coordinates just mean that there should be 6 equally-sized 'intervals' between the ordinates.

Hence, take x=...
0, π/6, 2π/6, 3π/6, 4π/6, 5π/6, 6π/6

i.e.
0, π/6, π/3, π/2, 2π/3, 5π/6, π

Howdu figure that out :O