9. Which of the following relations is a function? A. {(-1, - 4), (-1,0), (- 1,5), (- 1, 7), (- 1,9)}

B. {(-2, - 4), (-1, 7), (1, - 1), (1, 1), (3, 9)}

C. {(-4, 9), (- 3, 1), (- 2, 3), (- 2, 12), (0, 6)

D. {(0, - 4), (1, - 4), (2, 4), (3, 4), (4, - 4)}

step-by-step explanation:

the multiplicative inverse of a fraction a/b is b/a. for the multiplicative inverse of a real number, divide 1 by the number. for example, the reciprocal of 5 is one fifth 1/5 or 0.2, and the reciprocal of 0.25 is 1 divided by 0.25, or 4.

1/4 because there is 4 grades.