8 The graph of y = a cos(x + b) for 0
2
1
60
120
180
240
300
360
-1
-2
(a) Find the value of a and the value of b.
a
b =
(2)
Another curve C has equation y = f(x)
The coordinates of the minimum point of Care (4, 5)
(b) Write down the coordinates of the minimum point of the curve with
equation
(O y = f (2x)
(
..)
(y = f(x) - 7
(
I (2)
(Total for Question 8 is 4 marks)
Suppose that the price p (in dollars) and the weekly sales x (in thousands of units) of a certain commodity satisfy the demand equation 4p cubedplusx squaredequals38 comma 400. determine the rate at which sales are changing at a time when xequals80, pequals20, and the price is falling at the rate of $.20 per week.