PRACTICE (c) Given (k − 2) is the highest common factor
(HCF) of 18, 36 and 54. Find the value of k.
[3 marks]

k = 20

Step-by-step explanation:

Expressing 18, 36 and 54 as a product of their prime factors

18 = 2 × 3 × 3 = 2 × 3²

36 = 2 × 2 × 3 × 3 = 2² × 3²

54 = 2 × 3 × 3 × 3 = 2 × 3³

The common prime factors are 2 and 3²

HCF = 2 × 3² = 2 × 9 = 18

Thus

k - 2 = 18 ( add 2 to both sides )

k = 20

correct choice is b

step-by-step explanation:

when you calculate the average rate of change of a function, you are finding the slope of the secant line between the two points. for the function the average rate of change from point to point can be calculated as

to find the average rate of change from day 2 to day 10, note that at day 2, 8 houses were sold, so a(2,8) and at day 10, 2 houses were sold, so b(10,2). thus,