Решите неравенство методом интервалов: (x^2+4x-21)(x-5)>=0.

\[\left( x^{2} + 4x - 21 \right)(x - 5) \geq 0\]

\[x^{2} + 4x - 21 = (x + 7)(x - 3)\]

\[D_{1} = 4 + 21 = 25\]

\[x_{1} = - 2 + 5 = 3;\]

\[x_{2} = - 2 - 5 = - 7.\]

\[(x + 7)(x - 5)(x - 3) \geq 0\]

\[- 7 \leq x \leq 3;x \geq 5.\]