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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 answer
very 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 ago
3x( 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 ago
fine..
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 ago
in(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 ago
lets 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)