Physics, asked by Anonymous, 1 year ago

integration sin⁷x dx

Answers

Answered by abhi178
7
I =sin^7x.dx

=sin^6x .sinx.dx

= (sin²x)³.sinx.dx

=( 1 - cos²x)³sinx.dx

={1 -3cos²x +3cos⁴x - cos^6x}sinx.dx

=sinx.dx -3cos²xsinx.dx + 3cos⁴x.sinx.dx -cos^6x.sinx.dx

= -cosx + {3cos²x( -sinx).dx } -3/5{5cos⁴x(-sinx)dx +1/7{7cos^6x.(-sinx).} dx

[ you know , I think
I = f(x)^n.f(x)'.dx = f(x)^(n +1)/( n +1) ]

= - cosx +(cosx)³ -3/5(cosx)^5 + 1/7(cosx)^7 + Constant

Anonymous: yep :(
abhi178: I = sinx.dx -3cos²xsinx.dx +3cos⁴x.sinxdx -cos^6x.sinxdx
abhi178: you know sinx.dx = -cosx
Anonymous: yep that I know
Anonymous: i don't wanna hurt u but i am really confusing :(
abhi178: -3cos²x.sinx .dx = d(cos³x)/dx .dx
abhi178: where you confused
abhi178: tell me which step
Anonymous: 5th step
abhi178: ( a - b)³ = a³ - 3a²b+ 3ab² - b³
Answered by QGP
6
Here's the solution. Hope it helps.
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