Answer:
The slower plane has a speed of 450 km/h and the faster one has a speed of 900 km/h.
Step-by-step explanation:
Two planes:
The first one's speed is x
The second is y.
One plane is flying at twice the speed of the other.
I will say that y = 2x.
Two airplanes leave an airport at the same time, flying in the same direction
Same direction, so their relative speed is the subtraction of their speeds. 2x - x = x.
Means that after 1 hour, they will be x miles apart.
If after 4 hours they are 1800 km apart, find the speed of each plane
After 1 hour, x km apart. After 4, 1800. So
1 hour - x km apart
4 hours - 1800 km apart
4x = 1800
x = 1800/4
x = 450
2x = 2*450 = 900
The slower plane has a speed of 450 km/h and the faster one has a speed of 900 km/h.
Answer:
y = -x +4
Step-by-step explanation:
The y-intercept of the line is at +4, so the only viable choice is the last choice.
___
Each of the equations is shown in slope-intercept form:
y = mx + b
where b is the y-intercept, the y-value when x=0. The graph shows that as point (0, 4). So, the equation you're looking for is ...
y = (some x-term) +4
If you want to spend more brain power on the problem, you can compute the slope of the line as ...
m = ∆y/∆x = (1-4)/(3-0) = -3/3 = -1
Now, you know for sure the equation of the line is ...
y = -x +4
-.5 + 2, you can think of this as 2 - .5 as well, it would equal out to be 1.5.
