Question

which is the solution set of $-2d < 20$?
a) ${d|d < -10}$
b) ${d|d > -10}$
c) ${d|d > 10}$
d) ${d|d < 10}$

Explanation:

Step1: Solve the inequality \(-2d < 20\)

When dividing both sides of an inequality by a negative number, the direction of the inequality sign flips. Divide both sides by \(-2\):
\(d > \frac{20}{-2}\)

Step2: Simplify the right - hand side

Calculate \(\frac{20}{-2}=-10\). So the solution to the inequality \(-2d < 20\) is \(d > - 10\), which can be written in set - builder notation as \(\{d|d > - 10\}\)

Answer:

B) \(\{d|d > - 10\}\)