Answer:
93 o 39.
Explanation:
Hola.
En este caso, podemos resolver este problema por medio del planteamiento de las siguientes ecuaciones:
1. Definimos <em>x</em> como el primer dígito y <em>y</em> como el segundo, por lo tanto, como su suma es 12, escribimos:
<em>x</em> + <em>y</em> = 12
2. Ahora, dado que el primer dígito, x es el triple del segundo, escribimos:
<em>x</em> = 3 <em>y</em>
De este modo, podemos resolver para <em>y</em>:
3 <em>y</em> + <em>y</em> = 12
4 <em>y</em> = 12
<em>y</em> = 12 / 4
<em>y</em> = 3
Y para <em>x</em>:
<em>x</em> = 3 <em>y</em>
<em>x</em> = 3 * 3
<em>x</em> = 9
Así, el número puede ser 93 o 39.
¡Saludos!
You can reason it out like this:
-- The car starts from rest, and goes 8 m/s faster every second.
-- After 30 seconds, it's going (30 x 8) = 240 m/s.
-- Its average speed during that 30 sec is (1/2) (0 + 240) = 120 m/s
-- Distance covered in 30 sec at an average speed of 120 m/s
= 3,600 meters .
___________________________________
The formula that has all of this in it is the formula for
distance covered when accelerating from rest:
Distance = (1/2) · (acceleration) · (time)²
= (1/2) · (8 m/s²) · (30 sec)²
= (4 m/s²) · (900 sec²)
= 3600 meters.
_________________________________
When you translate these numbers into units for which
we have an intuitive feeling, you find that this problem is
quite bogus, but entertaining nonetheless.
When the light turns green, Andy mashes the pedal to the metal
and covers almost 2.25 miles in 30 seconds.
How does he do that ?
By accelerating at 8 m/s². That's about 0.82 G !
He does zero to 60 mph in 3.4 seconds, and at the end
of the 30 seconds, he's moving at 534 mph !
He doesn't need to worry about getting a speeding ticket.
Police cars and helicopters can't go that fast, and his local
police department doesn't have a jet fighter plane to chase
cars with.
Answer:
solving for: velocity
equation: velocity = distance / time
substitution: velocity = 1425 km / 12.5 hrs
answer: 114 km/hr
