Edexcel A2 C4 Mathematics June 2015 - Official Thread

Could someone check this is right please?
for the last question,
y= 3^x, dy/dx = 3^xln3
when x =2 dy/dx = 9ln3
so tangent=
y-9=9ln3(x-2)
y= 9ln3x-18ln3+9
so it cuts the x axis where
9ln3x-18ln3+9=0
9ln3x= 9-18ln3
ln3x= 1-2ln3
3x= e^1-2ln3
3x= e/ln9
x = e/3ln9

How many marks was this?

if the last question i didnt change 3^2x to 9^x but the method was right, how many marks would i lose?

I had a STEP exam right after as well

You've worked out where it crosses the y axis...


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Do you guys think i can get an A* if I have 68-C3 67-C4.

if the last question i didnt change 3^2x to 9^x but the method was right, how many marks would i lose?

ma bad i ****ed up, sorry for calling you out :c

My answers for this paper were:
1) 2+5x/4-25x^2/64
3rt2/2
181/128
2)(2x-3y)/(3x+8y)=dy/dx
+-(24/5,16/5)
3)x=4ln(2)
12+32ln(2)^2-32ln(2)
4) A=5,1,3
p=15
31.82
d=7.46
5)27/32
a=2 b=-5
6)k=4
4pi/3 + rt(3)/2
7) 1/(p-2) - 1/p
0.473
8) x=2 - 1/ln3
area = 13pi/ln3
this is most of the questions that i wrote down my answers to, I am confident in most of them although I am prone to the occasional stupid mistake so if you disagree then I will not argue with you.

How many marks do you think I will lose for the last question? I integrated the curve correctly, getting 40pi/ln3. But when calculating the volume of the cone I accidentally used (2-1/ln3) and did not use (2-(2-1/ln3)) for the height, so when I subtracted the 2 volumes, I got (67pi-54(pi)ln3)/ln3.