Maths--functions..

[XPFMember]

Assalamoalaikum!!

need help with function type questions of P1....and those like in the form of a + b sin x...and sketching part....if sumeone has concise notes plz let me know soon...have an exam tom!!
Jazak Allah Khair!

 

[XPFMember]

have a doubt in Q:5 (ii) of June 2010 first variant =>http://www.xtremepapers.net/CIE/International A And AS Level/9709 - Mathematics/9709_s10_qp_11.pdf
y is the greatest value 2?? shudnt it be 7...??

 

[ahmed t]

2-5cos^2(X)
you may have not noticed the squared and took x=pi
that would give u a value of -3(minimum)
any value cos^2(x) would be positive and would be subtracted from the two so to find the greatest value u musnt subtract any thing 2-0 is 2
u must have forgotten about the square

 

[XPFMember]

but when we draw the graph...the max. value os 7 :S

 

[soumayya]

we don't learn how to sketch graph of cos^2 in A level..

 

[XPFMember]

ok...but see the eqn we get is 2 - 5 cos^2 x..

can anybody give a detailed explanation..as to how we get the greatest value as 2....

 

[soumayya]

When x=pi/2, f(x)= 2-0 = 2
2 is the greatest positive value we can get...

 

[XPFMember]

i got it...actually i forgot that cos pi = -1 but cos^2 (pi) will be +1

Jazak Allah Khair!!

 

[soumayya]

u're welcome..

 

[ahmed t]

yea thats why i said in my first reply that u must of forgotten the squared sign

 

[XPFMember]

yeah..but that time too...i failed to spot my mistake ..
now when soumayya said greatest value is at pi/2...i was going to say it is at pi...but then i found that it isn't at pi...

anyways Jazak Allah Khair

btw u r doing A levels or AS?? and which subjects?

 

[ahmed t]

im takin A-level math only
already took chemistry and physics in november
it gets boring when there isnt much to study