Question
Factorise:
$5 x^2-16 x-21$
$5 x^2-16 x-21$
✓
Answer
$5 x^2-16 x-21$
$=5 x^2+5 x-21 x-21$
$=5 x(x+1)-21(x+1)$
$=(x+1)(5 x-21)$
$=5 x^2+5 x-21 x-21$
$=5 x(x+1)-21(x+1)$
$=(x+1)(5 x-21)$
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