Wednesday, October 23, 2013

int_1^2 x^4lnx dx Use integration tables to evaluate the definite integral.

To evaluate the integral problem: int_1^2 x^4ln(x) dx , we follow the formula from basic integration table. For the integrals with logarithm, the problem resembles the formula:
int x^n ln(x) dx = x^((n+1)) ( ln(x)/(n+1)- 1/(n+1)^2), n!= -1 .
By comparison of x^n with x^4 ,  we let n=4 which satisfy that condition n!=-1 to be able to use the aforementioned integral formula.
 Then the integral problem is evaluated as:
int_1^2 x^4ln(x) dx= [x^((4+1)) ( ln(x)/(4+1)- 1/(4+1)^2)]|_1^2
= [x^(5) ( ln(x)/5- 1/5^2)]|_1^2
= [x^(5) ( ln(x)/5- 1/25)]|_1^2
= [(x^(5) ln(x))/5- x^5/25]|_1^2
Apply definite integral formula: F(x)|_a^b = F(b) - F(a) .
[(x^(5) ln(x))/5- x^5/25]|_1^2=[(2^(5) ln(2))/5- 2^5/25]-[(1^(5) ln(1))/5- 1^5/25]
=[(32 ln(2))/5- 32/25]-[(1ln(1))/5- 1/25]
=(32 ln(2))/5- 32/25 -(1ln(1))/5+ 1/25
= (32 ln(2))/5 -0/5+ (1-32)/25
 
=( 32ln(2))/5 -31/25 or 3.196 (approximated value).

No comments:

Post a Comment

Summarize the major research findings of "Toward an experimental ecology of human development."

Based on findings of prior research, the author, Bronfenbrenner proposes that methods for natural observation research have been applied in ...