C3 and C4 DOUBTS HERE!!!

[-Cornea]

do i need to know how to prove that sin(A+B)=sinA cosB + cosA sinB =D because i can't get it from the book =(

[The Golden Girl =D]

Give me a couple of minutes to type it down ..Okies

[ Will be editing so check after some time ]


My teacher told me that there is no need for me to know How to prove this but if it's the Opposite of what my teacher said then please do tell me how we rpove it (:

I hope I helped

[-Cornea]

and i need to ask if u know what marks should i get in order to score an A* in my AL's if u have an idea about this ,i'll be grateful =}

[Malak]

^It all depends on the grade boundary for that year.
But generally you need to get an A in AS in order to get an A* overall and ,I guess, you need like 90% or above in A2 to get an A*
summary: A in AS and 90% (or above) in A2 = A* overall 

[-Cornea]

y = 2 – e?^-x iam really confused in these stuff should i multiply it -1 and then add 2 or should i multiply it by 1 only and add 2 then :s

[Malak]

y = 2 – e?^-x iam really confused in these stuff should i multiply it -1 and then add 2 or should i multiply it by 1 only and add 2 then :s

I dont understand the question :S
Can you be more clear? What does the question say?

[The Golden Girl =D]

Cornea ,if you're talking about how we Calculate the  y = 2 - e^-x  USING the calculator then  Here is the Method :


You press shift on the ln button then Multiply it by -X , and THEN add 2 to it

I hope I helped (:

[-Cornea]

no i mean they asked me to sketch it

[The Golden Girl =D]

Cornea can you send me your e-mail ID via PMs cuz It seems my graph can't attach for some weird reason =/

[-Cornea]

done i sent you my email

[Malak]

Good luck everyone for C3 2morrow

[Adzel]

Solve for x :

4e^2x + 3e^x = 1

Anyone?  

[astarmathsandphysics]

Sub y=e^x then y^2=e^2x
4y^2+3y-1=0
(4y-1)(y+1)=0
so 4y-1=0 so y=1/4 so e^x =1/4 so x=ln(1/4)
or y+1=0 so y=-1 so e^x=-1 so x=ln(-1) no solution

[Adzel]

I did the same thing, but in the answers; it has a solution and it's a negative number 

[astarmathsandphysics]

yes ln(1/4) is negative
-1.386