Explanation :
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Factorizes:
⇒ a² + 8a + 16 = 0.
As we know that,
Factorizes the equation into middle term splits, we get.
⇒ a² + 4a + 4a + 16 = 0.
⇒ a(a + 4) + 4(a + 4) = 0.
⇒ (a + 4)(a + 4) = 0.
⇒ (a + 4)² = 0.
⇒a=-4.
Hence a=-4.