If ∫_0^2 2 e^2 x dx =∫_0^a e^x dx, the value of ' a ' is:

If $\displaystyle \int_{0}^{2} 2 \mathrm{e}^{2 \mathrm{x}} \mathrm{dx}=\int_{0}^{\mathrm{a}} \mathrm{e}^{\mathrm{x}} \mathrm{dx}$, the value of ' a ' is :