Easy Integration :( (1 Viewer)

[Forbidden.]

Umm.. I think that requires substitution which is actually then 3 unit and if they haven't given you wat to sub in for what then it's 4 unit.

I would do

let x = 5 sin@
dx = 5cos@ d@

integral (25 - 25 sin²@)^(1/2) .5 cos@ d@
= integ [25(1 - sin²@)]^(1/2) .5 cos@ d@
= integ 5cos@ .5cos@ d@
= integ 25 cos²@ d@
and cos2@ = 2cos²@ - 1 (3 unit double the angle)
therefore, cos²@ = 1/2 (cos2@ + 1)

so integ. 25/2 [cos2@ + 1] d@
= 25/4(sin2@ + @) + C

holy shit thats what i learnt in first year second semester maths

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[tacogym27101990]

holy shit thats what i learnt in first year second semester maths

Rock On

you didnt learn substitution at high school???

 

[Forbidden.]

holy shit thats what i learnt in first year second semester maths

Rock On

this is trig substitution.
i used polynomial substitution like u = 4 - x², du = - 2x dx

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[tacogym27101990]

o so you didnt do 4 unit??

 

[Forbidden.]

o so you didnt do 4 unit??

up to 3 unit ... i wish i did 4 unit tho back in skool

Rock On.

 

[tacogym27101990]

how come you didnt??
you seem to love maths