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## Main Question or Discussion Point

Ive seen some example of U substitution where the limits of integration are changed for example, Say we have a particle pushed along the x axis with force=10/(1+x)^2 and we want the work required to move it 9 ft.

so Work = the integral from [0,9] of 10/(1+x)^2(dx) U substitution gives

u=1+x

du=dx

the 10 is factored out tilll the end.

Ok so, in this example at x=0, U=1 and at x=9, U=10

Now the new limits are [1,10] instead if [0,9]. But Why?

so Work = the integral from [0,9] of 10/(1+x)^2(dx) U substitution gives

u=1+x

du=dx

the 10 is factored out tilll the end.

Ok so, in this example at x=0, U=1 and at x=9, U=10

Now the new limits are [1,10] instead if [0,9]. But Why?