Question

∫(0→正无穷)e^(-2x)dx=?

Answer 1

答：
(0→∞) ∫ e^(-2x)dx
=(0→∞) (-1/2) ∫ e^(-2x) d(-2x)
=(0→∞) (-1/2)e^(-2x)
=0-(-1/2)
=1/2