The body is thrown upward at a speed of 25m / s. How long does it take to reach a height of 20m?

The distance traveled by the body with equal slow motion can be calculated using the formula:
S = V0 * t – g * t² / 2, where S is the distance traveled by the body (S = 20 m), V0 is the initial velocity of the body (V0 = 25 m / s), g is the acceleration of gravity (we take g = 10 m / s²), t1 is the lifting time of the body (s).
Let us express and calculate the lifting time of the body:
g * t² / 2 – V0 * t + S = 0.
10 * t² / 2 – 25 * t + 20 = 0.
t² – 5 * t + 4 = 0.
According to Vieta’s theorem, we determine the lifting time of the body: t1 = 4 s, t2 = 1 s.
Answer: t1 = 4 s, t2 = 1 s.