Three polynomials are factored below, but some coefficients and constants are missing. All of the missing values of a, b, c, and
d are integers.
1. x² + 2x 15 = (ax + b)(cx + d)
2. 2x³ + 6x² 20x = 2x(ax + b)(cx + d)
3.9x² +21x + 6 = (ax + b)(cx + d)
Fill in the table with the missing values of a, b, c, and d.