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Integration

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Original post by King-Panther
No, the fraction is 32x2 \frac{3}{2x^2}


not on the q33 im looking at it isnt :L

edit: but if the question had a fraction like that:

32x2=32x2 \frac{3}{2x^2} = \frac{3}{2}x^{-2}
(edited 12 years ago)
Original post by just george
not on the q33 im looking at it isnt :L

edit: but if the question had a fraction like that:

32x2=32x2 \frac{3}{2x^2} = \frac{3}{2}x^{-2}


My bad, i have a mac so isn't compatible with this document, thus hard to read...

So, how would i go about it?


3x36x2+2x1 {3}x^{-3} - {6}x^{-2} + {2x} - 1
(edited 12 years ago)
Original post by King-Panther
My bad, i have a mac so isn't compatible with this document, thus hard to read...

So, how would i go about it?


3x36x2+2x1 {3}x^{-3} - {6}x^{-2} + {2x} - 1


same way you would if the powers were positive :smile: times it by the power, then take 1 off the power.

e.g. ddx3x3=9x4 \frac{d}{dx}3x^{-3} = -9x^{-4} :smile:
Original post by just george
same way you would if the powers were positive :smile: times it by the power, then take 1 off the power.

e.g. ddx3x3=9x4 \frac{d}{dx}3x^{-3} = -9x^{-4} :smile:


So I got

9x2+12x1+2 -9x^{-2} + 12x^{-1} + 2
Original post by King-Panther
So I got

9x2+12x1+2 -9x^{-2} + 12x^{-1} + 2


No you need to take one away from the power :smile: so -3 goes to -4, -2 goes to -3 etc..
Original post by just george
No you need to take one away from the power :smile: so -3 goes to -4, -2 goes to -3 etc..


Ahh, I need to integrate it?

So I got

3x36x3+2x 3x^{-3} - 6x^{-3} + 2x
(edited 12 years ago)
Original post by just george
No you need to take one away from the power :smile: so -3 goes to -4, -2 goes to -3 etc..


i got you
(edited 12 years ago)
when you differentiate you take one away from the power

so if the power is 2 (e.g. x^2) it differentiates to 2x (because 2 - 1 = 1)

so if the power is -3 (e.g. x^-3) it differentiates to -3x^-4 (because -3 - 1 = -4)

easy to get confused by it but it actually makes perfect sense :smile:
Original post by just george
when you differentiate you take one away from the power

so if the power is 2 (e.g. x^2) it differentiates to 2x (because 2 - 1 = 1)

so if the power is -3 (e.g. x^-3) it differentiates to -3x^-4 (because -3 - 1 = -4)

easy to get confused by it but it actually makes perfect sense :smile:


I got you, my mind was elsewhere...

I got

9x4+12x3+2 -9x^{-4} + 12x^{-3} + 2 which = 0 @ turning point

I subbed in -2,-1,0,1,2 and none equaled 0
are we still on question 33?

because that question is 13x332x2+2x1 \frac{1}{3}x^3-\frac{3}{2}x^2+2x-1 :L
Reply 90
Original post by King-Panther
I got you, my mind was elsewhere...

I got

9x4+12x3+2 -9x^{-4} + 12x^{-3} + 2 which = 0 @ turning point

I subbed in -2,-1,0,1,2 and none equaled 0


Which question is it?
Original post by just george
when you differentiate you take one away from the power

so if the power is 2 (e.g. x^2) it differentiates to 2x (because 2 - 1 = 1)

so if the power is -3 (e.g. x^-3) it differentiates to -3x^-4 (because -3 - 1 = -4)

easy to get confused by it but it actually makes perfect sense :smile:


for Q)33

Its suppose to be, once you differentiate it

x26x+2 x^{2} - 6x + 2
Original post by just george
are we still on question 33?

because that question is 13x332x2+2x1 \frac{1}{3}x^3-\frac{3}{2}x^2+2x-1 :L


Yes, thats the one, i think I may have confused you,

y = 13x332x2+2x1 \frac{1}{3}x^3-\frac{3}{2}x^2+2x-1 :L


dydx=x26x+2 \frac{dy}{dx} = x^{2} - 6x + 2

Original post by raheem94
Which question is it?
Original post by raheem94
Which question is it?


Your thoughts on 36
Reply 94
Original post by King-Panther
Your thoughts on 36


Area =13(x2+1)dx \displaystyle = \int^3_1 (x^2+1)dx

As we need to find area hence we need to integrate the expression, with limits.
Original post by raheem94
Area =13(x2+1)dx \displaystyle = \int^3_1 (x^2+1)dx

As we need to find area hence we need to integrate the expression, with limits.


= 4

Q)37 = -9

how about Q)38.... normal is tangent right?
(edited 12 years ago)
Reply 96
Original post by King-Panther
= 4

how about Q)38.... normal is tangent right?


No, the area is not 4.
Original post by raheem94
No, the area is not 4.


y=x2+1 x^{2} + 1

dy/dx= 2x 2x right?

but im suppose to integrate

so its x^3/3 + 1x
(edited 12 years ago)
Reply 98
Original post by King-Panther
y=x2+1 x^{2} + 1

dy/dx= 2x 2x right?


We have to integrate not differentiate.
Original post by King-Panther
Yes, thats the one, i think I may have confused you,

y = 13x332x2+2x1 \frac{1}{3}x^3-\frac{3}{2}x^2+2x-1 :L



dydx=x26x+2 \frac{dy}{dx} = x^{2} - 6x + 2

should be a -3x instead of -6x i think :smile:

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