integration substitution (1 Viewer)

[shuning]

the question says u may use the substitution of u=x-2

 

[Timothy.Siu]

/
| 2xdx/root(4x-x^2)
/

u=x-2 x=u+2
u^2=x^2-4x+4
4x-x^2=4-u^2
du=dx

/
| 2(u+2)du/root(4-u^2)
/

4 S du/root(4-u^2) + S 2udu/root(4-u^2)

=4sin^-1-1 (u/2) - S dA/root A where A=4-u^2

=4sin^-1-1 (u/2) - 2rootA

and sub everything back in, i know theres a better way but i think this is right....

 

[GUSSSSSSSSSSSSS]

would ya look at that it is right below lol

its too late for me to try lol
sorry shuning

maybe try it tomorrow and talk to you on monday lol

 

[tommykins]

 

[shuning]

would ya look at that it is right below lol

its too late for me to try lol
sorry shuning

maybe try it tomorrow and talk to you on monday lol

we both joined this forum on the aug of 2008, but no way u have more post counts than me !!!!!!!!! :jaw:

 

[jet]

Tommykins... youve made a mistake with your substitution...

Shouldn't it be u + 2 in the denominator?

 

[vds700]

i think u = x - 2 is right.

The final answer I get is

 

[Aerath]

i think u = x - 2 is right.

The final answer I get is

Yup, that's my answer too:

 

[shuning]

Yup, that's my answer too:

so is mine

 

[Timothy.Siu]

so is mine

good work lol

 

[shuning]

good work lol

ty la

 

[tommykins]

Tommykins... youve made a mistake with your substitution...

Shouldn't it be u + 2 in the denominator?

yeah the (x-2) should be u, my bad.