INICIALMENTE - - - > V1 , d = 240 km , t1LUEGO - - - >"su velocidad aumenta en 20 km / h" - - - > V2 = V1 + 20.
(1) "tarda 2 horas menos en recorrer la MISMA Distancia" d = 240 km t2 = t1 - 2.
(2)_SOLUCION_inicilamente - - - - - - - - > V1 = d / t1 - - - - > V1 = 240 / t1.
(3)luego - - - - - - - - - - - - - - - - - >V2 = d / t2 - - - - > V2 = 240 / t2 - - - - - - - - - - (4)4 ecuaciones con 4 incognitas, ya se puede resolver.
Reemplazo la ec.
(1) en (4) - - - - > V1 + 20 = 240 / t2.
(5)reemplazo las ec.
(3) y (2) en (5) - - - - - - - - - > 240 / t1 + 20 = 240 / t1 - 2LISTO (unica incognita es "t1"), resolviendo.
<img src="https://tex.z-dn.net/?f=%5Cfrac%7B240%7D%7Bt1%7D%20%2B20%3D%5Cfrac%7B240%7D%7Bt1-2%7D%3D%3E%20%5Cfrac%7B240%2B20t1%7D%7Bt1%7D%3D%5Cfrac%7B240%7D%7Bt1-2%7D%3D%3E%28240%2B20t1%29%2A%28t1-2%29%3D%28240%29%2At1%3D%3E240%2At1%2B20%2A%28t1%29%5E2-480-40%2At1%3D240%2At1" /> \ frac{240 + 20t1}{t1} = \ frac{240}{t1 - 2} = >(240 + 20t1) * (t1 - 2) = (240) * t1 = >240 * t1 + 20 * (t1) ^ 2 - 480 - 40 * t1 = 240 * t1" alt = " \ frac{240}{t1} + 20 = \ frac{240}{t1 - 2} = > \ frac{240 + 20t1}{t1} = \ frac{240}{t1 - 2} = >(240 + 20t1) * (t1 - 2) = (240) * t1 = >240 * t1 + 20 * (t1) ^ 2 - 480 - 40 * t1 = 240 * t1" align = "absmiddle" class = "latex - formula"><img src="https://tex.z-dn.net/?f=2%2A%28t1%29%5E2-4%2At1-48%3D0" /><img src="https://tex.z-dn.net/?f=%28t1-6%29%2A%282t1%2B8%29%3D0" />t1 = 6 horas RESP.
Reem.
En (3)V1 = 240 / 6V1 = 40 km / h RESP.