Question

To solve the inequality -1/2 k is greater then or equal to -5, Danny multiplied both sides by the
reciprocal of -1/2 . His solution was k is greater then or equal to 10.What mistake did he make?

Danny checked his solution, but his check did not let him know that he had
made an error.What number could he have substituted?

c. Find a number that satisfies the original inequality but not Danny’s solution

Answer 1

Danny forgot to reverse the inequality sign.

c. (-1/2)k >= -5.
Multiply both sides by -2:
k <= 10.