Answer:
x = - 2, x = 9
Step-by-step explanation:
Given
f(x) = 
The denominator of f(x) cannot be zero as this would make f(x) undefined.
Equating the denominator to zero and solving gives the values that x cannot be.
x² - 7x - 18 = 0
(x - 9)(x + 2) = 0
Equate each factor to zero and solve for x
x + 2 = 0 ⇒ x = - 2
x - 9 = 0 ⇒ x = 9
The excluded values are x = - 2, x = 9
190 min.................................
Answer: 
Step-by-step explanation:
The confidence interval for population mean is given by :-

Given : Sample size : n= 35 , large sample (n>30)
Mean difference : 
Standard deviation : 
Significance level : 
Critical value : 
Now, the 99.9% confidence interval for the mean difference between the marks scored last week and marks scored this week by all the students will be :-

Hence, the 99.9% confidence interval for the mean difference between the marks scored last week and marks scored this week by all the students = 
Square numbers are numbers with an odd number of factors. For example, 1 and 4 are square numbers.