What is the indefinite integral of xlog(x)?

The integral can be split into two different functions of x which is a hint that we must use the integration by parts method. The method is defined as ∫ uv’ dx = uv - ∫ u’v dx. If we let u = log(x) and v’ = x and then solve for u’ and v such that u’ = 1/x and v = (1/2)x^2 , we can substitute in the values to find the solution. ∫ u’v dx = (1/2)(x^2)log(x) - ∫ (1/x)*((1/2)x^2) dx then goes to ∫ u’v dx = (1/2)(x^2)log(x) - ∫ (1/2)x dx which solves as ∫ u’v dx = (1/2)(x^2)log(x) - (1/4)x^2 + C and can be simplified to read as ∫ u’v dx = (1/4)(x^2)(2log(x) - 1) + C.

WH

Related Maths A Level answers

All answers ▸

If a curve has equation y = (-8/3)x^3 - 2x^2 + 4x + 18, find the two x coordinates of the stationary points of this curve.


Prove that 1+2+...+n = n(n+1)/2 for all integers n>0. (Hint: Use induction.)


Why do the trig addition formulae work?


Below is a question from the Edexcel Maths Core 1 textbook, Solve the equation x^2 + 8x + 10 = 0 using completing the square.