\(\displaystyle \frac{1}{5} \int_1^5 te^{-t^2}\ dt.\)
=\(\displaystyle \frac{1}{5} \int_0^-25 e^{u}\ \frac{-1}{2}du\)
where \(\displaystyle u=-t^2, du=-2t dt, dt= \frac{-1}{2} du\)
what I don't understand is why the bounds on the intergal change from 5 to -25 when the u substitution is made can some please let me know?
=\(\displaystyle \frac{1}{5} \int_0^-25 e^{u}\ \frac{-1}{2}du\)
where \(\displaystyle u=-t^2, du=-2t dt, dt= \frac{-1}{2} du\)
what I don't understand is why the bounds on the intergal change from 5 to -25 when the u substitution is made can some please let me know?