We want to solve the given equation by factoring. Let's consider our equation.
9d^2-81=0
Notice that this equation follows a special pattern. It can be factored as a difference of squares. Let's factor the equation!
We found that the solutions to the given equation are d=- 3 and d=3. To check our answer, we will graph the related function, y=9d^2-81, using a calculator. Note that the calculator will use the variable x instead of d.
We can see that the x-intercepts are - 3 and 3. Therefore, our solutions are correct.
