In Example 9(a), change the coefficient of the first term from 20 to 5 and then factor.

Data from Example 9(a)

In factoring 20x² − 45, note a common factor of 5 in each term. Therefore, 20x² − 45 = 5(4x² − 9). However, the factor 4x² − 9 itself is the difference of squares. Therefore, 20x² − 45 is completely factored as 20x ² − 45 = 5(4x² − 9) = 5(2x + 3)(2x − 3)