Question

raffle tickets are being sold for a fundraiser. The relationship between n, number of raffle tickets sold, and A, amount of money in dollars raised, is given by the function below. A(n)=3n-20 What is the equation of the inverse function N(a)?

Answer 1

D. N(a) = (a + 20)/3

Explanation:

A(n) = 3n - 20

A is a function of n. The inverse will be: N is a function of a.

Change A(n) to y and n to x.

y = 3x - 20

Switch x and y.

x = 3y - 20

Solve for y.

x + 20 = 3y

3y = x + 20

y = (x + 20)/3

Now switch y to N(a) and x to a.

Answer: N(a) = (a + 20)/3

Answer 2

The inverse is (n+20)/3

Explanation:

a(n) = 3n - 20

Let this equal y

y = 3n-20

Exchange y and n

n = 3y-20

Solve for y

add 20 to each side

n+20 = 3y-20+20

n+20 = 3y

Divide each side by 3

(n+20)/3 = 3y/3

(n+20)/3 = y

The inverse is (n+20)/3