Answer:
x-60
Step-by-step explanation:
You have to factor out the quadratic.
You know that one of the factors is x-40.
To factor:
Find a number that when added to -40, gives you -100, and also when multiplied, gives you 2400.
That such number is -60.
Add an x before it, and you get (x-60)
So the question is asking: (x-4)(x-2)
because there is a bracket in between the two expressions it means we have to multiply them together: (x-4) x (x-2)
you can break down the question into smaller parts:
x multiply x
x multiply -2
-4 multiply x
-4 multiply -2
here are the answers:
x^2 (means x squared)
-2x
-4x
8 (because when you multiply two negative numbers it makes a positive)
now you put it into an expression (this is expanding):
x^2 - 2x - 4x + 8
to simplify it you collect like terms:
x^2 - 6x + 8
The above is the answer :)
Answer:
FG = 7
Step-by-step explanation:
5x+2+3x-1=9
8x+1=9
8x = 8
x = 1
FG = 5(1)+2 = 7
No because think about 12 and 6. the greatest common factor is 3 which isn't even
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.
