2:14 3:21 etc. all you have to do is for every 1 you add to the front number add 7 more to the second number
Answer: ![t\in [\dfrac{1}{4},2]](https://tex.z-dn.net/?f=t%5Cin%20%5B%5Cdfrac%7B1%7D%7B4%7D%2C2%5D)
Step-by-step explanation:
Given
Inequality is 
Taking variables one side
Using wavy curve method
OK, so the graph is a parabola, with points x=0,y=0; x=6,y=-9; and x=12,y=0
Because the roots of the equation are 0 and 12, we know the formula is therefore of the form
y = ax(x - 12), for some a
So put in x = 6
-9 = 6a(-6)
9 = 36a
a = 1/4
So the parabola has a curve y = x(x-12) / 4, which can also be written y = 0.25x² - 3x
The gradient of this is dy/dx = 0.5x - 3
The key property of a parabolic dish is that it focuses radio waves travelling parallel to the y axis to a single point. So we should arrive at the same focal point no matter what point we chose to look at. So we can pick any point we like - e.g. the point x = 4, y = -8
Gradient of the parabolic mirror at x = 4 is -1
So the gradient of the normal to the mirror at x = 4 is therefore 1.
Radio waves initially travelling vertically downwards are reflected about the normal - which has a gradient of 1, so they're reflected so that they are travelling horizontally. So they arrive parallel to the y axis, and leave parallel to the x axis.
So the focal point is at y = -8, i.e. 1 metre above the back of the dish.
Answer:more people will be living in Africa than in Asia sometime around 2120
Step-by-step explanation:
Answer:
Time(min)
2
6
8
15
Distance(km)
6
18
24
45
Step-by-step explanation:
the time is 1/3rd of the distance. it's a 1:3 ratio
