Answer:
-5-1
Step-by-step explanation:
Answer:
i will say 15 and -7
Step-by-step explanation:
15+-7=8 and 15--7=22
15+-7 so take the negative and take out that mush of the big number
15-7=8
15--7= the subtracting beside a negative makes it changes to positive and addition so 15+7=22
1 km = 1000 meters.
Find total meters: 80 km x 1000 meters per km = 80,000 meters.
Divide total meters by the given speed:
80,000 meters / 180 m/s = 444.44 seconds.
1 minute = 60 seconds
444.44. Seconds / 60 seconds per minute = 7.41 minutes = 7 minutes 24.42 seconds
Total time = 7 minutes 24.42 seconds
Round as needed.
Solve cos(4x)-cos(2x)=0 ∀ 0<=x<=2pi ..............(0)
Normal solution:
1. use the double angle formula to decompose, and recall cos^2(x)+sin^2(x)=1
cos(4x)=cos^2(2x)-sin^2(2x)=2cos^2(2x)-1 .................(1)
2. substitute (1) in (0)
2cos^2(2x)-1-cos(2x)=0
3. substitute u=cos(2x)
2u^2-u-1=0
4. Solve for x
factor
(u-1)(u+1/2)=0
=> u=1 or u=-1/2
However, since cos(x) is an even function, so solutions to
{cos(2x)=1, cos(-2x)=1, cos(2x)=-1/2 and cos(-2x)} ...........(2)
are all solutions.
5. The cosine function is symmetrical about pi, therefore
cos(-2x)=cos(2*pi-2x),
solution (2) above becomes
{cos(2x)=1, cos(2pi-2x)=1, cos(2x)=-1/2, cos(2pi-2x)=-1/2}
6. Solve each case
cos(2x)=1 => x=0
cos(2pi-2x)=1 => cos(2pi-0)=1 => x=pi
cos(2x)=-1/2 => 2x=2pi/3 or 2x=4pi/3 => x=pi/3 or 2pi/3
cos(2pi-2x)=-1/2 => 2pi-2x=2pi/3 or 2pi-2x=4pi/3 => x=2pi/3 or x=4pi/3
Summing up,
x={0,pi/3, 2pi/3, pi, 4pi/3}
It is now possible to find the margin of error, the reason being that the confidence level is not given. However the 'standard error' of the sample mean can be found as follows:

Converted to a percentage, we get 1.11% which is the third choice of answer.