# Integral of cumulative age distribution curve

1. Jul 14, 2010

### dabeedo

How do you integrate 2exp(1-x).dx?

The expression describes the cumulative number of cells as a function of cell age (0 newborn, 1 at division) in an exponentially growing culture.

Thanks for any help.

Dave

2. Jul 14, 2010

### HallsofIvy

Let u= 1- x so that du= - dx.
$$\int 2 e^{1-x} dx= -2\int e^u du$$