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integral of xe^-x dx

Using integration by parts by letting u=x and dv/dx=e^-x. this implies that du/dx=1 and v=-e^-xThe By Parts formulae is u.v - integral(v.du/dx) = -xe^-x - integral(-e^-x).1 dx = -xe^-x + integral(e^-x) dx = ...
BK
Answered by Brandon K. • Maths tutor
8134 Views

Sean drives from Manchester to Gretna Green. He drives at an average speed of 50 mph for the first three hours. He then breaks and drives the final 150 miles at 30 mph. Sean thinks his average speed is 40 mph ,is he correct?

This is a relatively complicated mechanics question requiring the student to put aside their initial assumption and work with the actual meaning of average speed. In order to do this the student must find ou...
AB
Answered by Adam B. • Maths tutor
7289 Views

A square is placed in a circle of area (49π)cm^2 such that all four vertices of the square lie on the circumference of the circle. What is the area of the square?

It's always helpful to draw a diagram beforehand.Since we know the area of the circle is (49π)cm 2 , we can work out the radius using A=πr 2 . Rearranging, we get r = 7cm. Add this information to our diagram...
KS
Answered by Karnan S. • Maths tutor
5639 Views

Make x the subject of the formula y=(4x+5)/x

xy=4x+5 xy-4x=5x(y-4)=5x=5/(y-4)
RP
Answered by R P. • Maths tutor
5490 Views

The gradient of a curve is given by dy/dx = 3 - x^2. The curve passes through the point (6,1). Find the equation of the curve.

Since we differentiate a function to find the gradient of a curve at any point, we need to reverse that to find the equation of the curve. We do this by integrating with respect to x:If you have a constant (...
DN
Answered by Darya N. • Maths tutor
10965 Views