Answer :
2.) 7a^2 + 50a + 7 = 7a^2 + a + 49a + 7 = a(7a + 1) + 7(7a + 1) = (a + 7)(7a + 1)
3.) 3x^2 + 11x - 20 = 3x^2 - 4x + 15x - 20 = x(3x - 4) + 5(3x - 4) = (x + 5)(3x - 4)
4.) x^2 + 7x - 18 = x^2 - 2x + 9x - 18 = x(x - 2) + 9(x - 2) = (x + 9)(x - 2)
3.) 3x^2 + 11x - 20 = 3x^2 - 4x + 15x - 20 = x(3x - 4) + 5(3x - 4) = (x + 5)(3x - 4)
4.) x^2 + 7x - 18 = x^2 - 2x + 9x - 18 = x(x - 2) + 9(x - 2) = (x + 9)(x - 2)