The equation is .

Add 18d to each side.

Apply commutative property: .

The general factor trinomial form is .

In the above trinomial, .

Since c is positive and b is positive, you need to find two positive factors with a sum of 18 and product of 56.

Make an organized list of the factors of 56, and look for the pair of factors with a sum of 18.

Apply the pattern form: when .

because .

The factor form of equation is .

Apply zero product property: .

Solve the first equation, .

Solve the second equation, .

Check for first solution:

To check the solution, the value of substitute in original equation, .

                 (Solution checks)

Check for second solution:

To check the solution, the value of substitute in original equation, .

                 (Solution checks)

The value of .