Question
Expand the following$:(a + 4) (a + 7)$
✓
Answer
$(a + 4) (a + 7)$
$= a^2+ 4a + 7a + 28$
$= a^2 + 11a + 28$
$($Using identity : $(x + a) (x + b))$
$= x^2 + (a + b) x + ab).$
$= a^2+ 4a + 7a + 28$
$= a^2 + 11a + 28$
$($Using identity : $(x + a) (x + b))$
$= x^2 + (a + b) x + ab).$
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