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# P3 Easy Integration watch

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1. Hi, just trying to check my answer, whats the integral between x=2, x=0 of:

-1 + (1/2)/(1+X) + (5/2)/(3-x)

Find the answer in the form p+qlnr

Ive done it but need to check my answer, Thanks.
2. (Original post by ResidentEvil)
Hi, just trying to check my answer, whats the integral between x=2, x=0 of:

-1 + (1/2)/(1+X) + (5/2)/(3-x)

Find the answer in the form p+qlnr

Ive done it but need to check my answer, Thanks.
Well -i got:

-x + 0.5ln((1+x)/(3-x)^5)
3. Is that what you have got - cos i am doubting what i have done
4. (Original post by ResidentEvil)
Hi, just trying to check my answer, whats the integral between x=2, x=0 of:

-1 + (1/2)/(1+X) + (5/2)/(3-x)

Find the answer in the form p+qlnr

Ive done it but need to check my answer, Thanks.
-x+0.5ln|2+2x|-2.5ln|6-2x| is what I get for the integration.
5. So i got:

-2 + 0.5 ln 729
6. (Original post by Silly Sally)
So i got:
-2 + 0.5 ln 729
I also get that answer. Since 729 = 3^6, it simplifies to -2 + 3 ln(3).
7. i got -1+3ln3
8. (Original post by lexazver203)
i got -1+3ln3
(int from 0 to 2) -1 + (1/2)/(1 + x) + (5/2)/(3 - x) dx
= [ -x + (1/2) ln(1 + x) - (5/2) ln(3 - x) ] (from 0 to 2)
= -2 + (1/2) ln(3) + (5/2) ln(3)
= -2 + 3 ln(3).
9. omg u all got diffferent answers !

(Original post by Jonny W)
(int from 0 to 2) -1 + (1/2)/(1 + x) + (5/2)/(3 - x) dx
= [ -x + (1/2) ln(1 + x) - (5/2) ln(3 - x) ] (from 0 to 2)
= -2 + (1/2) ln(3) + (5/2) ln(3)
= -2 + 3 ln(3).
Johnny tell me HOW exactly is
integral of +(5/2)/(3-x)
= -(5/2)ln(3-x)?
10. (Original post by ResidentEvil)
omg u all got diffferent answers !

Johnny tell me HOW exactly is
integral of +(5/2)/(3-x)
= -(5/2)ln(3-x)?
to do it in a lengthly method:

use u=(3-x) => du = -dx

(5/2)/(3-x) = (5/2)/u

=> integral (5/2)/(3-x) = integral (5/2)/u -du = -5/2 integral 1/u du
= -5/2 ln(u) = -5/2 ln(3-x)
11. (Original post by ResidentEvil)
omg u all got diffferent answers !

Johnny tell me HOW exactly is
integral of +(5/2)/(3-x)
= -(5/2)ln(3-x)?
keep (5/2) out of the integral sign, sonce it is a constant, so you get:

(5/2) [int 1/(3-x) dx]

intgral of 1/(3-x) is -ln(3-x)

so multiplying by the constant gives, (-5/2)ln(3-x)
12. ohh is it because of the "-x"??
13. (Original post by ResidentEvil)
ohh is it because of the "-x"??
yeah

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