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First we need to find derivative
`dy/dt=-cos t+tsin t-1`
Here we've used product rule to differentiate `-tcos t.`
Now we insert `dy/dt` and `y` into the initial value problem.
`t(-cos t+tsin t-1)=-tcos t-t+t^2sin t`
`-tcos t+t^2sin t-t=-tcos t-t+t^2sin t`
Obviously, the left and the right sides are equal to each other meaning that the solution satisfies the differential equation. Now we only need to check the initial condition.
`y(pi)=-pi cos pi-pi=-pi(-1)+pi=pi-pi=0`
Therefore, `y=-tcos t-t` satisfies both the differential equation and the initial condition meaning it is the solution to our initial value problem.
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