Answer: 3rd one
Rearrange the original equation so it fits the model of : ax^2+bx+c=0
Then use the quadratic formula to find all possible answers.
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:
Step-by-step explanation:
we can use the distributive property and get
and we can add like terms
and know we divide both sides by 16.5
and doing the dvision we get that
so their are 6 adults and 24 kids because when you add 18+6 and get 24
then you multiply 6(24) because adult tickets are 24 and get 144
then you multiply 24(12) because student tickets are half as much as parents so they are 12 and you multiply by 24 kids and get 288
then you add 288 student tickets total price +144 adult ticket total price =432 total cost fro all tickets
The answer is 40, take 21 from the last equation solved and add 8 to it then add 11
