Answer:
[tex] \frac{( {w} - {3}) }{( {w} - 7) } [/tex]
Step-by-step explanation:
[tex] \frac{ {w}^{2} - 9 }{ {w}^{2} - 4w - 21 } \\ \\ = \frac{ {w}^{2} - {3}^{2} }{ {w}^{2} - 7w + 3w- 21 } \\ \\ = \frac{( {w} + {3}) ( {w} - {3}) }{w( {w} - 7) + 3(w- 7) } \\ \\ = \frac{( {w} + {3}) ( {w} - {3}) }{( {w} - 7) (w + 3) } \\ \\ = \frac{( {w} - {3}) }{( {w} - 7) } [/tex]
