Agreed!

Task. How long did the trip to Ryazan?

175
Answer:
Let S₁ and S₂ , V₂ and V₁, t₁ and t₂, respectively, distance, speed and time on the first and second parts of the path. pogda average speed all the way: n( S₁ + S₂) / (t₁ + t₂) = (S₁ + S₂) / (S₁ / V₁ + S₂ / V₂) = 56. puwede new symbols: x = V₁ = S₂, y = V₂ = S₁ in accordance with the requirement of numerical equality. The result is the equation n(y + x) / (y / x + x / y) = 56, after conversion n(56 – y)x2 - у2х + 56у2 = 0. imeem quadratic equation with two unknown integer values. povodom in the equation y = 50, we find the root x = 350. vicissim you visit, n50/350 + 350/50 = 1/7 + 7 (hours). proverka: 400/(1/7 + 7) = 56 (km).
177
Answer add
To write questions and answers you need to register on the site