Tricky A level maths questions?

Minnie16

Please explain how I'm supposed to get a correct answer for these questions with working out, thank you.

(edited 7 years ago)

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Reply 1

NotNotBatman

For 2.) Consider

(a-b)^2\geq 0

as the square of any real number is greater than or equal to 0.

For 1.) and 2.) Just start from

a\geq b

and see if it holds true, remember when multiplying by a negative number, you have to switch the inequality sign.

(edited 7 years ago)

Reply 2

RDKGames

Study Forum Helper

Original post by Jas1947

Please explain how I'm supposed to get a correct answer for these questions with working out, thank you.

For the first one; (1) remember that when you multiply inequalities by -1 on both sides, the sign flips. (2) Move the 2ab on the opposite side and you can factorise all of it into

(a-b)^2\geq0

and think about what happens given a's relationship to b. (3) I'm sure you can spot what you can do to both sides there.

For the second one; use triangles or the unit circle to work out the values of

tan(\frac{3}{4}\pi)

and

sin(\frac{\pi}{2})

(then raise this value to the 10th power). I'm sure you can work out what log(100) is. E will obviously be something less than 1 raised to the 10th power so it goes down even more. This leaves D where you can approximate what power goes onto the 2 in order to get 10, doesn't have to be exact. Once you have all these the largest one should be obvious.

Nothing tricky here.

(edited 7 years ago)

Reply 3

Minnie16

Original post by RDKGames

For the first one; (1) remember that when you multiply inequalities by -1 on both sides, the sign flips. (2) Move the 2ab on the opposite side and you can factorise all of it into

(a-b)^2\geq0

tan(\frac{3}{4}\pi)

and

sin(\frac{\pi}{2})

For the first question , the last equation with c, if i divide bith sides by c then wouldnt I just get a≥b again?

Reply 4

RDKGames

Study Forum Helper

Original post by Jas1947

For the first question , the last equation with c, if i divide bith sides by c then wouldnt I just get a≥b again?

Yep

Reply 5

Minnie16

Original post by RDKGames

Yep

So 1,2 and 3 must all be true?

Reply 6

RDKGames

Study Forum Helper

Original post by Jas1947

So 1,2 and 3 must all be true?

By the looks of it. Have a bit more confidence, man, you already established which ones are true. :tongue:

(edited 7 years ago)

Reply 7

Minnie16

Original post by RDKGames

By the looks of it. Have a bit more confidence, man, you already established which ones are true. :tongue:

I thought so but the answer says E which confuses me because I thought it should be H instead..

Reply 8

RDKGames

Study Forum Helper

Original post by Jas1947

I thought so but the answer says E which confuses me because I thought it should be H instead..

If c was negative then that statement would be false, but if it's positive then it's correct. They should realistically define c as being either positive or negative.

Edit: I misinterpreted the question (DAMN YOU 2AM), it says for any real number so c can be either negative or positive for the statement to hold true. Since it's only true for ONE of these cases rather than both, it is technically incorrect.

(edited 7 years ago)

Reply 9

drandy76

C can also be negative, which is why it's E not H

Posted from TSR Mobile

Thank you

Q2) Just work them out, what is

\tan(3{\pi}/4)

etc. (think of the graphs). You should know the standard trig answers e.g.

\sin({\pi}/2)

\mathrm{arcsin}(\dfrac{1}{2})

also you should know how to workout logs as well, e.g. the standard approach I use is that the base, in the examples' case 10, what power of 10 gives me the inside of the bracket? well 10^2 = 100 so