C1 and C2 DOUBTS HERE!!!!!

[narnia]

Find the sum of all the integers between 1 and 1000 which are divisible by 7.
help plz..=/

And 7th question, part (d) of the attached worksheet...how to do??!

[Shazizzzle]

Find the sum of all the integers between 1 and 1000 which are divisible by 7.
help plz..=/

And 7th question, part (d) of the attached worksheet...how to do??!

Sum of integers from  1 to 1000 divisible by 7, right?
We know that the 7 times table is 7, 14, 21 etc.
So consider the sequence
7 + 14 + 21 + ...

Now we need to know how many terms are divisible by 7 in 1000 integers, so simply divide 1000 by 7 using long division. You get 142.8, so basically only 142 terms in 1000 are divisible by 7.

Find the sum of those 142 terms!
a=7, d=7, n=142
Sn =  142/2 (2(7) + (142-1) (7))
Sn = 71,071.

[8T]

JUNE 08 q.9  C2
Can anyone explain it pleaseee ?

[Malak]

JUNE 08 q.9  C2
Can anyone explain it pleaseee ?

It would take really long to write the whole thing so I have uploaded my answers
If u dont understand any thing in it then i can surely help

for part a since x-20 was in a bracket i found the angles and then at the end subtract the 20, i dont know if there is any other way to solve it but i do it this way

same idea is for part b
In part b u times the range by 3 as the angle given is 3x, always do that when the angle is a multiple like 2x or 3x or whatever and at the end MAKE SURE to divide all your found angles by 3 to find x ('cause you found angle for 3x before)

[8T]

It would take really long to write the whole thing so I have uploaded my answers
If u dont understand any thing in it then i can surely help

for part a since x-20 was in a bracket i found the angles and then at the end subtract the 20, i dont know if there is any other way to solve it but i do it this way

same idea is for part b
In part b u times the range by 3 as the angle given is 3x, always do that when the angle is a multiple like 2x or 3x or whatever and at the end MAKE SURE to divide all your found angles by 3 to find x ('cause you found angle for 3x before)

Thank you

[Malak]

Thank you

Welcome

[Malak]

Q10 part c

Thx

[wakemeup]

Q10 part c

Thx

Ah yes, I appeared in this exam and I remember feeling particularly frustrated in this Q, even though it's quite easy now that I think about it. All you have to do is actually draw the circle. You already know that the line passes through the midpoint of the radius and you know that it' parallel to the tangent i.e it'd perpendicular to the radius. Using Pythagorean theorem, (take half the radius as perpendicular and the radius as the hypotenuse) you can now easily find the length of the line.

Hope that helps

[mdwael]

Can someone please explain how to solve this question? I have attached a picture  with the question in it. Its page 140 question 28 in our C2 textbook and I cant seem to get it right. I think it is flawed in the first place... 

[Ghost Of Highbury]

Can someone please explain how to solve this question? I have attached a picture  with the question in it. Its page 140 question 28 in our C2 textbook and I cant seem to get it right. I think it is flawed in the first place... 

3/x = x+8/3
x^2+8x = 9
x^2+8x-9=0
x^2-x+9x-9=0
x(x-1)+9(x-1)=0
x = -9, x = 1


common ratio = when x =1 -> 3 ; when x = -9 -> -1/3

sum to infinity existsif |r| < 1
that means r = -1/3

fifth term = ar^4 = 3
a = 3/(-1/3)^4 = 243

sum to infinity = a/1-r = 182.25

[mdwael]

3/x = x+8/3
x^2+8x = 9
x^2+8x-9=0
x^2-x+9x-9=0
x(x-1)+9(x-1)=0
x = -9, x = 1


common ratio = when x =1 -> 3 ; when x = -9 -> -1/3

sum to infinity existsif |r| < 1
that means r = -1/3

fifth term = ar^4 = 3
a = 3/(-1/3)^4 = 243

sum to infinity = a/1-r = 182.25

What you have said is partially corret according to the text book.. I got the same working as yours but the text book says: when X=1 r=1/3 and when X= -9 r= -3

your first term is correct.. 243..

Sum of infinity according to the txt book is 364.5 not 182.25 as you said and what I am getting aswell..

[The Golden Girl =D]

Q10 part c

Thx

I know My paper is messy but I hope you get it

Attached.

I hope I helped

[mdwael]

Can someone solve and explain? its page 140 question 27 in the edexcel C2 text book. I attached the question in a photo.

[**RoRo**]

Do we need to know how to prove the sine rule and cosine rule as well as the trigonometric angles (30, 45 and 60) ?

[Malak]

Do we need to know how to prove the sine rule and cosine rule as well as the trigonometric angles (30, 45 and 60) ?

I dont think so u need to know how to prove them, only how to apply them..and about the angles, if ur talking about the ratio/triangle thingi, i guess same is for that, just how to use it.

And Thx both of you, i understood