I cannot see Zoe's work to explain the error, but the correct method of solving is listed:
x is the number of 30-second ads
y is the number of 60-second ads
x+y=12(60)=720 would be the first equation; this is because while the ads together make 12 minutes, the ad times are in seconds. This means we must multiply 12 by 60.
y=2x is the second equation
Our system is then
x+y=720
y=2x
We will use substitution to solve this. Plug 2x in place of y in the first equation:
x+2x = 720
Combine like terms:
3x = 720
Divide both sides by 3:
3x/3 = 720/3
x = 240
Substitute this value in for x in the second equation:
y=2(240)
y=480
They buy the van for £8,500 + VAT 20%:
Total paid for the van = £8,500 x 1.20 = £10,200
They make 12 payments of £531.25 for a total of:
12 x £531.25 = £6,375
To find the amount of deposit, subtract the total payments from total cost:
£10,200 - £6,375 = £3,825
The ratio of deposit to the payments is: 3825 : 6375
Reduce the answer by dividing both numbers by 75:
3825/75 = 51
6375 / 75 = 85
The ratio becomes: 51/85
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Answer:</h2>
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Step-by-step explanation:</h2>
The graphs of 
can be obtained from the graph of the cosine function using the reciprocal identity, so:
But in this problem, the graph stands for the function:
Because the period is now 4π as indicated and for 
in the figure and this can be proven as follows:
Also, 
as indicated in the figure and this can be proven as:
Answer:
Z = 8 + 2x2 + 2y2
Convert to polar coordinates
Z = 8 + 2r2
Now theta will go from 0 to pi/2 because it's in the first quadrant.
R will go from 0 to the radius of the circle formed at the intersection of the plane and the paraboloid.
14 = 8 + 2r2
r = sqrt(3)
So r goes from 0 to sqrt(3).
You integrate 14-z where 0<r<sqrt(3) and 0<theta<pi/2.
It is 14-z and not z because just z would give the volume under the paraboloid.
Step-by-step explanation: please go answer my recent question
