How do you solve the inequality #–9(x – 2) < –72#?
Notice that the direction of inequality has changed because either side was divided by a negative number.
Double negative equals positive, and
of direction changes because as a rule if a negative number is multiplied or divided to both sides of an inequality the sense of direction changes.
Solution set: S =
This can be checked by substituting any number greater than positive 10 into the original inequality, say 11, and we have
which is true!