Mathematics: Post your doubts here!

[abcde]

^ I don't get "maximum of sin x is 1"? And "minimum of six x is -1" ? Is it the same for Cos too?

Do you remember the graphs of sin x and cos x? Check this: http://regentsprep.org/Regents/math/algtrig/ATT7/sincostan.htm
Yes, the maximum of both sin x and cos x is 1 and the minimum for both is - 1.

 

[CaptainDanger]

Do you remember the graphs of sin x and cos x? Check this: http://regentsprep.org/Regents/math/algtrig/ATT7/sincostan.htm
Yes, the maximum of both sin x and cos x is 1 and the minimum for both is - 1.

Right thanks...

 

[elbeyon]

Please help me I really need help on the Q. no 5(i) of the below mentioned paper. (Please explain in details the method)


Question Paper :- http://www.xtremepapers.com/CIE/International A And AS Level/9709 - Mathematics/9709_w08_qp_1.pdf


Marking Scheme :-
http://www.xtremepapers.com/CIE/International A And AS Level/9709 - Mathematics/9709_w08_ms_1.pdf

 

[memyself15]

Please help me I really need help on the Q. no 5(i) of the below mentioned paper. (Please explain in details the method)


Question Paper :- http://www.xtremepapers.com/CIE/International A And AS Level/9709 - Mathematics/9709_w08_qp_1.pdf


Marking Scheme :-
http://www.xtremepapers.com/CIE/International A And AS Level/9709 - Mathematics/9709_w08_ms_1.pdf

greatest value of cos is 1 and minimum value is -1.
multiply the inequality by -b bcoz the range is given in x.
as you are multiplying inequality by negative so the inequality signs change.
the new inequality becomes: -b (less than sign) -bcosx (greater than sign)b
now multiply it by a : a-b(less than) a-bcosx (greater than) a+b
thus, minimum value: a-b which is given -2 and maximum value : a+b which is equal to 10.
now solve both equtions.
hope that helps.

 

[CaptainDanger]

Please help me I really need help on the Q. no 5(i) of the below mentioned paper. (Please explain in details the method)


Question Paper :- http://www.xtremepapers.com/CIE/International A And AS Level/9709 - Mathematics/9709_w08_qp_1.pdf


Marking Scheme :-
http://www.xtremepapers.com/CIE/International A And AS Level/9709 - Mathematics/9709_w08_ms_1.pdf

Maximum of Cos is 1 and Minimum of Cos is -1.

You have to form two equations and then solve them simultaneously...

Maximum
10=a-b (1)
10=a-b

Minimum
-2=a-b(-1)
-2=a+b

Solve them simultaneously... You will get the answers...

 

[elbeyon]

@Captain: I have already tried the way you mentioned but it gives the wrong answer ( Check in Marking scheme and Examination Report). Anyway thanks
@memyself15: I didn't got what you actually are trying to say. Can you please elaborate it. Please and Thank you too.

Others also, please help me.

 

[CaptainDanger]

C

@Captain: I have already tried the way you mentioned but it gives the wrong answer ( Check in Marking scheme and Examination Report). Anyway thanks
@memyself15: I didn't got what you actually are trying to say. Can you please elaborate it. Please and Thank you too.

Others also, please help me.

Oh... Read the question again it says they are positive constants....

By the way you can do it the other way...

When you sketch the graph of it... The maximum point is going to be at 180... And minimum at 0 or 360... So put 180 at x for the maximum equation and for minimum either put 0 or 360 in the equation at x both will give you the same answer...

The equations you get will be

10=a-b cos 180

and

-2=a-b cos 0

solve using these...

 

[Unicorn]

when finding the domain of a function does the the y value have to be positive?
E.G.
6/2x + 1.5=y the answer says from 0<x ≤2 but i put anything but 0 it gives a value

but anything above 2 is negative so does it have to be positive?

 

[CaptainDanger]

when finding the domain of a function does the the y value have to be positive?
E.G.
6/2x + 1.5=y the answer says from 0<x ≤2 but i put anything but 0 it gives a value

but anything above 2 is negative so does it have to be positive?

I don't get what you exactly want to know? This question is from?

 

[aliya_zad]

can sumone help me wid the 2nd part of it..

 

[XPFMember]

View attachment 3284
can sumone help me wid the 2nd part of it..

As-salam-o-alaikum!

(x^2 + ax + 1)(x^2 - ax - 1) = 0

So x^2 + ax + 1 = 0 and x^2 - ax - 1 = 0

Hence solve...

 

[aliya_zad]

walaikumusalam..
yes i did equate them to zero but dunno how to get the markscheme answers

 

[Unicorn]

I don't get what you exactly want to know? This question is from?

i want to know if when finding the domain does the y value obtained from x have to be positive?

[question 11 ii]

 

[unique840]

walaikumusalam..
yes i did equate them to zero but dunno how to get the markscheme answers View attachment 3285

value of a=3
so x^2 + 3x + 1 = 0 x^2 - 3x - 1 = 0
x = [-b +- (b^2 - 4ac)^0.5] / 2a x = [-b +- (b^2 - 4ac)^0.5] / 2a
x = {-3 +- [(3)^2 - 4(1)(1)]^0.5} / 2(1) x = {3 +- [(-3)^2 - 4(1)(-1)]^0.5} / 2(1)
x = {-3 +- (5)^0.5} / 2 x = {3 +- (13)^0.5} / 2

 

[aliya_zad]

value of a=3
so x^2 + 3x + 1 = 0 x^2 - 3x - 1 = 0
x = [-b +- (b^2 - 4ac)^0.5] / 2a x = [-b +- (b^2 - 4ac)^0.5] / 2a
x = {-3 +- [(3)^2 - 4(1)(1)]^0.5} / 2(1) x = {3 +- [(-3)^2 - 4(1)(-1)]^0.5} / 2(1)
x = {-3 +- (5)^0.5} / 2 x = {3 +- (13)^0.5} / 2

OMG this iz like so easy....
thank you!!

 

[unique840]

OMG this iz like so easy....
thank you!!

ur welcum

 

[CaptainDanger]

i want to know if when finding the domain does the y value obtained from x have to be positive?

[question 11 ii]

Not necessarily... It can come as negative too...

 

[Unicorn]

Not necessarily... It can come as negative too...

then why does the answer have them between these two values? yet i put anything greater/less than the limit it still works :$

 

[CaptainDanger]

then why does the answer have them between these two values? yet i put anything greater/less than the limit it still works :$

Obviously the values will come... But you can't take them as domain of the given function...

 

[Silent Hunter]

Question about S1:

Might seem easy but i cant get it

The letters of the word POSSESSES are written on nine cards, one on each card. The cards are shuffled and four of them are selected and arranged in a straight line.

(a) How many possible selections are there of the four letters?
(b) How many arrangements are there of the four cards?

Thank You