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can you integrate this....?
3x(4x-1)^1/2 using the method of changing variables! Give the answer in its simplest form
6 Answers
- 1 decade agoFavourite answervery easy girl... see , first use, 4x-1=t^2; then , integration willl become- (3/4) * t (t^2 + 1); then open all the brackets and solve; i think now u can do it. 
- CPUcateLv 61 decade ago3x( 4x - 1)^1/2 let ( 4x - 1)^1/2 = t 4x - 1 = t^2 x = 1/4( t^2 + 1 ) . . . . . substitute 3x( 4x - 1)^1/2 = 3/4 ( t^2 + 1 ) t^2 integ 3/4 ( t^4 + t^2 ) dt = 3/4 ( t^5/5 + t^3/3 ) . . . . = 3/4 [ (4x -1)^3/2 + 4x -1 ] 
- 1 decade agofine.. let 4x-1=t^2. it implies 4dx= 2tdt implies dx=t/2 *dt. now the integrand becomes 3*[t^2+1]/4 *t * t/2*dt now u can proceed ..........( just open the brackets and integration becomes easy. actually its a difficult job to write down each step. so a little hint may be sufficient for catching the problem. 
- 1 decade agoin(3x(4x-1)^1/2)dx Let u^2=4x-1 2udu=4dx 4x=u^2-1 3/8*int( (u^2+1)*u*u) du =3/8 in(u^4+u^2 )du = 3/8*(u^5/5+u^3/u)+c where u=sqrt()4x-1) 
- 1 decade agolets take 4x-1=t^2 x= t^2/4+1/4 dx= 2t/4=t/2 now 3x(4x-1)^1/2 becomes 3(t^2/4+1/4)(t)(t/2) expanding 3/8t^4+3/8t^2 integration gives you 3/40 (t^5) + 3/24 (t^3) ie 3/4(t^3)(t^2+1/6) ie 3/4(4x-1)^3/2(4x-5/6) 



