The function is:
f ( x ) = x² - x - 72
This is a quatdratic function. So we can find the zeroes of the function with the formula:
x 1/2 = ( - b +/- √(b² - 4 ac) ) / ( 2a )
And we have: a = 1, b = - 1 and c = - 72
x 1/2 = ( 1 +/- √((-1)² - 4 · 1· ( - 72 )) ) / 2
x 1/2 = ( 1 +/- √( 1 + 288 ) ) / 2
x 1/2 = ( 1 +/- √289 ) / 2
x 1/2 = ( 1 +/- 17 ) / 2
x 1 = ( 1 - 17 ) 2 = - 16 / 2 = - 8
x 2 = ( 1 + 17 ) / 2 = 18 / 2 = 9
Answer: The zeroes are - 8 and 9.
Step-by-step explanation:
5 students in choir <=> 1 student in band
If there are 47 students in band =>
47×5 = 235 students in choir (B)
We have been given for a normal distribution the mean time it takes to walk to the bus stop is 8 minutes with a standard deviation of 2 minutes. And the mean time it takes for the bus to get to school is 20 minutes with a standard deviation of 4 minutes.
(a) Average time that it would take reach school can be obtained by adding the average times.
8+20 = 28 minutes.
(b) Standard deviation of the trip to school can be found as:

Therefore, standard deviation of the entire trip is 4.47 minutes.
(c) Let us first find z score corresponding to 30 minutes.
We need to find the probability such that 
Therefore, the required probability is 0.67.
(d) If average time to walk to school is 10 minutes, then overall average time for the trip will be 10+20 = 30 minutes.
(e) Standard deviation won't change it will remain 4.47
(f) The new probability will be:


Therefore, probability will be 0.50.
[5(14-2)^2]/2=
(5•12^2)/2=
5•144/2=
5•72=
720/2= 360
7/6
it’s positive because it’s going up