The formula of the kinetic energy is:

where m is a mass of the object, v is speed of the object at the moment of time. So we have:

The answer is
2000 Joules.
4x + 4 < 4x + 3 (expand it)
4 < 3 (cancel 4x on both sides)
Since 4 < 3 is not true there is no solution.
Answer: NO SOLUTION.
Explanation:
Constant speed means that the object is covering equal distance in equal interval of time. The motion is called uniform motion for such case. In this problem, it is given that an object is moving with a constant speed of 8 m/s. It means that it does not change its speed. It is moving with a single speed constantly.
We can say that it moves 8 meters every second or 800 cm every second.