Решите уравнение:
а) (х - 1)(х - 7) = 0;    г) (х + 1)(х - 1)(х - 5) = 0;
б) (х + 2)(х - 9) = 0;   д) х(х + 3)(х + 3) = 0;
в) (х - 11)(x + 6) = 0; е) (х - 4)(х + 9)(х + 13) = 0.

Решение:


a) (x - 1) (x - 7) = 0: x - 1 = 0 => x = 1, x - 7 = 0 => x = 7 => x = 1; 7.
б) (х + 2) (х - 9) = 0: х + 2 = 0 => х = -2, х - 9 = 0 => х = 9 => х = -2; 9.
в) (х - 11) (x + 6) = 0: х - 11 = 0 => х = 11, х + 6 = = 0 => х = -6 => х = -6; 11.
г) (х + 1) (х - 1) (х - 5) = 0, х + 1 = 0 => х = -1, x - 1 = 0 => х = 1, х - 5 = 0 => х = 5 => х = -1; 1; 5.
д) х • (х + 3)(х + 3) =0: х = 0, х + 3 = 0 => х = -3 => х = -3; 0.
е) (х - 4) (х + 9) (х + 13) = 0: х - 4 = 0 => х = 4, х + 9 = 0 => х = -9, x + 13 = 0 => х = -13 => х = -13; -9; 4.