MCQ
If $x^{2}-x-42=(x+k)(x+6),$ then $k=$
- A$6$
- B$-6$
- C$7$
- ✓$-7$
✓
Answer
Correct option: D.
$-7$
$x^{2}-x-42$
$=x^{2}-7 x+6 x-42$
$=x(x-7)+6(x-7)$
$=(x-7)(x+6) \therefore k=-7$
$=x^{2}-7 x+6 x-42$
$=x(x-7)+6(x-7)$
$=(x-7)(x+6) \therefore k=-7$
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