he velocity function

*v*(

*t*) (in meters per second) is given for a particle moving along a line.

a) Find the displacement

*d*1 traveled by the particle during the time interval given above.

b) Find the total distance

*d*2 traveled by the particle during the time interval given above.

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I found a) is -7.5, but I'm a bit confused by integrals. I don't understand how calculating the area under the graph finds "displacement" (I'm a bit confused about what displacement actually means in this kind of a question). And I have no idea how to approach part b (it doesn't even sound like it should involve integrals).