The velocity function is v(t)= -t^2 +4t -3 for a particle moving along a line. Find the displacement (net distance covered) of the particle during the time interval [-1,6].

I've tried integrating the function and then plugging in the values.

Also I tried factorizing the function and dividing the integral based on the negative and positive sign and then integrating and plugging the values.

But none of the methods give the right answer. Anybody got other ideas?