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Calc. 2 question! help me please!?
i have no clue to how to start with this integration:
Integration of SquareRoot(2x-x^2) dx
2 Answers
- Old TeacherLv 79 years agoFavorite Answer
I would rewrite by completing the square:
INT[ sqr(2x-x^2)] dx= INT { sqr[1-(x-1)^2] } dx
Now use trig substitution,
Sin(u)= (x-1)/1= x-1
Sqr[1-(x-1)^2] = cos(u)
X= sinu + 1
Dx = cosu du
INT [ cosu * cosu du]....remember that cos^2(u)= (1/2)(1+ cos(2u))
= INT [(1/2)* (1+ cos2u) ] du
= (1/2) [ u + (1/2)sin2u] + C.....remember that sin2u= 2sinucosu
= (1/2)[ u + sinucosu ] + C
= (1/2) {sin^-1(x-1) + (x-1)* sqr[1-(x-1)^2]} + C
Hoping this helps!
- Man of SteelLv 69 years ago
factor out a x.
sqrt(x(2-x)).
INT[sqrtx*sqrt(2-x)]
u^2=x
2udu=dx
INT[u*sqrt(2-u^2)du]
trig sub.
u=sqrt(2)sinv
v=theta
du=sqrt(2)cosv
INT[sqrt(2)sinv*sqrt(2-2sin^2v) *sqrt(2)cosv dv]
INT[2sinvcosv*sqrt(2cos^2v) dv]
INT[2sinvcosv*sqrt(2)*cosv]
2sqrt(2)*INT[2sinvcos^2v dv]
u-sub. I am going to use t.
t=cosv
dt=-sinvdv
-2dt=2sindv
-4sqrt(2)*INT[t^2dt]
-4sqrt(2)*[1/3*t^3]
(-4/3)sqrt(2)*cos^3v.
hower remember
u=sqrt(2)sinv
u/sqrt(2)=sinv
draw a triangle.
cosv=sqrt[(2-u^2)/2)]
however remember
u=sqrtx
so plug that in and you will have your answer.