3U Maths Question Thread

[jakesilove]

Thanks:) Looks like another instance of me seriously needing to memorize the log laws oops

Aha definitely worth doing

[jakesilove]

Got it, thanks Jake! <3

Anytime

[atar27]

Hey, thank you so much but is there a clearer way because I can't seem to understand what your saying. Sorry about that.

What do you sub in or take as a common factor to get 1/3?

[RuiAce]

What do you sub in or take as a common factor to get 1/3?

At the factorising step, the common factor was 1/3 k (k+1). From the first term, k-1 was left behind. From the second term, 3 was left behind.

That was the transition from line 2 to line 3

Note that earlier on I multiplied the second term by 3/3. That's how I made the 1/3 appear.

Whilst at the start it is tricky and I'm not heavily against working on both sides, if you've just started induction I will need to say that you need to improve your skills in algebra further for the rest of 3U.

[MysteryMarker]

Don't really know how to go about this question.

Cheers.

[jakesilove]

Don't really know how to go about this question.

Cheers.

Hey! With Binomial questions like this, I generally start by just brute forcing the shit out of it.





When we subtract the first relationship from the second relationship, you'll notice that the positive terms cancel out, and the negative terms 'double', giving us the relationship we are trying to prove! Now, if n is odd, the final term will be negative. If n is even, the final term will be positive. If the final term is negative, it will 'double', but if it is positive it will cancel out, leaving the 'n-1' term! Does that all make sense?

[MysteryMarker]

Hey! With Binomial questions like this, I generally start by just brute forcing the shit out of it.





When we subtract the first relationship from the second relationship, you'll notice that the positive terms cancel out, and the negative terms 'double', giving us the relationship we are trying to prove! Now, if n is odd, the final term will be negative. If n is even, the final term will be positive. If the final term is negative, it will 'double', but if it is positive it will cancel out, leaving the 'n-1' term! Does that all make sense?

Yeah that all makes sense. Thank you so much, I tend to always struggle with these harder binomial theorem questions.

[RuiAce]

Yeah that all makes sense. Thank you so much, I tend to always struggle with these harder binomial theorem questions.

You might want to memorise that trick. Every now and then questions involving \(\binom{n}{k}\) have k going up by 2, and that's always how you deal with it.

[jamgoesbam]

Could someone please explain this question? Thank you!

Answer: D

[:3]

Struggling with these few :3.

[RuiAce]

Struggling with these few :3.
(Image removed from quote.)

Refer to post #253

[RuiAce]

Could someone please explain this question? Thank you!

Answer: D

[levendibigd]

Hey there! Could I get a hand with HSC question Q13a (iii)? I don't understand how they were able to get a value for the amplitude.

[imtrying]

Could I get a hand with this question please?

[RuiAce]

Could I get a hand with this question please?

Refer to post #752