How can we proof the second eqn of motion with the help of formula of AP ( sum up to nth term)

Example if a body is having u= 20m/s and have an acceleration of -1-/s^2 for 10 sec. Then how much displacement will it cover.

Solve this by using AP

Uniformly accelerated motion creates a AP( arithmetic progression) because velocity of the particle is increasing every second with a equal constant amount called common difference in AP.

So, to find nth velocity of the body just use AP's formula for finding nth term.

And for distance multiple that nth velocity with nth value of time.