Hi, I'm trying to prove that the integral of x^3 (x cubed) between the limits of a (lower limit) and b (upper limit) is: (b^4)/4 - (a^4)/4 I'm using the traditional method of dividing the area into n rectangles (where n tends to infinity). Hence the width of 1 rectangle is (b-a)/n The x coordinate (left side of each thin rectangle) of any rectangle is: a + (k-1) * ((b-a)/n) I can prove other integrations using this 'traditional' approach but cannot get the correct answer here. Does anyone have a link to the proof or can provide it? Thanks. This is driving me mad.