Question about answer in 13th edition FM manual for example of a continuous annuity with varying force of interest

Am I just not seeing what happened to the negative sign? I've written the question below, the part I was confused about was between the first and second step in the second equation.

Example 2 A 10-year annuity provides continuous payments at a rate of $$t^2$$ at time $$t$$. The force of interest is $$.03t^2$$. Write an expression in integral form for the present value of this annuity.

Solution In general, the present value of an $$n$$-year annuity with continuous payments at a variable force of interest $$\delta_t$$ is: $$PV =\int_{0}^{n} f(t)e^{-\int_{0}^t \delta_r dr} dt$$ where $$f(t)$$ is the rate of payment. In this case, we have: $$\int_{0}^{10} t^2e^{-\int_{0}^t .03r^2 dr} dt = \int_{0}^{10} t^2e^{[.01r^3]_0^t} dt = \int_{0}^{10} t^2e^{.01t^3} dt$$

Any clarification would be much appreciated!