Answer:
Correct choice is 
Step-by-step explanation:
1. If
then you can find the inverse 

2. If
then

3. Hence,

Cos9x - cos5x = -2sin2x.sin7x
sin17x - sin3x = 2sin7x.cos10x
so f(x) =

=
Answer:
x= -13
y= -28
Step-by-step explanation:
To find the two numbers, write a system of equations with x as one number and y as another:
x-y=15
5x=2y-9
Use substitution to substitute one equation into another. Then solve for the variable.
x=15+y into 5x=2y-9
becomes
5(15+y) = 2y-9
75+5y = 2y- 9
75+3y= -9
3y = -84
y= -28
To find x, substitute y= -28 into one equation.
x - (-28) = 15
x+28 =15
x = 15-28
x=-13
Answer:
(a - 3b)(a + 3b)
Step-by-step explanation:
a² - 9b²
(a)² - (3b)²
(a - 3b)(a + 3b)
Answer:
0.1875
Step-by-step explanation:
σM=σ/√N
=8/√7500
=8/86.608
=0.092
Z=(x-μ)/σ/√N
=(25.5-36)/8/√7500
=-10.5/0.0092=-1141.304
Z score = -1.3125
=(27-36)/8/√7500
=
=9/0.0092=978.261
Z score= -1.125
-1.125-(-1.3125)=-1.125+1.3125)= 0.1875
The probability that the sample mean will be between 25.5 and 27 years
P(between 25.5 and 27) = 0.1875