Solving indefinite integral by u-substitution, we follow:
int f(g(x))*g'(x) = int f(u) *du where we let u = g(x) .
By following the instruction to let "u" be the denominator of the integral,
it means we let: u = root(3)(x) -1
Find the derivative of "u" which is du = 1/(3x^(2/3))dx
Then du =1/(3x^(2/3))dx can be rearrange into 3x^(2/3)du =dx .
Applying u-substitution using u =root(3)(x)-1 and 3x^(2/3)du =dx .
int root(3)(x)/(root(3)(x)-1) dx = int root(3)(x)/u*3x^(2/3)du
= int (x^(1/3)*3x^(2/3))/udu
=int (3x^(1/3+2/3))/udu
=3 int x/udu
Note: x^(1/3+2/3) = x^(3/3)
=x^1 or x
Algebraic techniques:
From u = root(3)(x)-1 , we can rearrange it into root(3)(x)=u+1 .
Raising both sides by a power 3:
(root(3)(x))^3 =(u+1)^3
x = (u+1)*(u+1)*(u+1)
By FOIL: (u+1)*(u+1) = u*u +u*1+1*u+1*1
= u^2+u+u+1
= u^2+2u+1
Then let (u+1)(u+1) = u^2 +2u +1 in (u+1)(u+1)(u+1) :
(u+1)(u+1)(u+1) = (u+1)*(u^2+2u+1)
Applying distributive property:
(u+1)(u^2+2u+1) = u *(u^2+2u+1) + 1*(u^2+2u+1)
= u^3 +2u^2+u +u^2+2u+1
=u^3+3u^2+3u+1
then x = (u+1)*(u+1)*(u+1) is the same as
x =u^3+3u^2+3u+1
Substitute x=u^3+3u^2+3u+1 in 3 int x/udu :
3 int x/udu = 3 int (u^3+3u^2+3u+1 )/u du
= 3int (u^3/u+(3u^2)/u+(3u)/u+1/u) du
=3int (u^2+3u+3+1/u) du
Evaluating each term in separate integral:
3 * [ int u^2 *du+ int 3u*du+int 3*du+ int 1/u du]
where:
int u^2 *du = u^3/3
int 3u*du =(3u^2)/2
int 3*du = 3u
int 1/u du= ln|u|
3 * [ int u^2 *du+ int 3u*du+int 3*du+ int 1/u du] becomes:
3*[u^3/3 +(3u^2)/2 +3u+ln|u|] +C= 3u^3/3 +(9u^2)/2 +9u+3ln|u|+C
Substitute u = root(3)(x)-1:
3u^3/3 +(9u^2)/2 +9u+3ln|u| +C = (root(3)(x)-1)^3 +(9(root(3)(x)-1)^2)/2 +9(root(3)(x)-1)+3ln|(root(3)(x)-1)| +C
Thursday, September 27, 2018
int root(3)(x)/(root(3)(x) - 1) dx Find the indefinite integral by u substitution. (let u be the denominator of the integral)
Subscribe to:
Post Comments (Atom)
Why is the fact that the Americans are helping the Russians important?
In the late author Tom Clancy’s first novel, The Hunt for Red October, the assistance rendered to the Russians by the United States is impor...
-
Friar Lawrence plays a significant role in Romeo and Juliet's fate and is responsible not only for secretly marrying the two lovers but ...
-
Suppose that the average daily food consumption $F$ of a herbivorous mammal with body weight $x$, where both $F$ and $x$ are measured in pou...
-
Pablo Neruda's "Ode to My Socks" is full of figurative language, including similes and metaphors. Similes are figurative compa...
-
In the late author Tom Clancy’s first novel, The Hunt for Red October, the assistance rendered to the Russians by the United States is impor...
-
Resourceful: Phileas Fogg doesn't let unexpected obstacles deter him. For example, when the railroad tracks all of a sudden end in India...
-
Iago states in act 1, scene 1 that he is jealous Othello made Cassio his lieutenant. Iago believes he has had more battle experience and is ...
-
Evaluate $\displaystyle \int x^2 \cos mx dx$ by using Integration by parts. If we let $u = x^2$ and $dv = \cos mx dx$, then $d...
No comments:
Post a Comment