4c^2-a^2-6ab-9b^2

Question

factoring by grouping

Answer 1

4c² - a² - 6ab - 9b² = 4c² - (a² + 6ab + 9b²) = 4c² - (a + 3b)²

 

       = [2c - (a + 3b)][2c + (a + 3b)] = (2c - a - 3b)(2c + a + 3b)