Answer:
A = 46
B = 134
C = 78
Step-by-step explanation:
An equation can be used to predict values from a pattern by merely substituting any value to determine the equivalent value. An example is the geometric series which has a standard equation of an = a1 * r^(n-1) and is used to predict the nth term of the series
Answer:
-x + 10
Step-by-step explanation:
(x + 7) - (2x-3)
x + 7 - 2x - 3
x - 2x
-x + 7 + 3
-x + 10
Answer:
Venn diagrams, De'moivres rule and probability
Step-by-step explanation:
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.
