MCQ
Tick $(\checkmark)$ the correct answer:
$x^2 + 4x - 21 = ?$
$x^2 + 4x - 21 = ?$
- A$(x - 7)(x + 3)$
- ✓$(x + 7)(x - 3)$
- C$(x - 7)(x - 3)$
- D$(x + 7)(x + 3)$
✓
Answer
Correct option: B.
$(x + 7)(x - 3)$
B. $(x + 7)(x - 3)$
Solution:
$x^2 + 4x - 21$
$= x^2+ 7x - 3x - 21$
$= x(x + 7) - 2(x + 7)$
$= (x - 3)(x + 7)$
Solution:
$x^2 + 4x - 21$
$= x^2+ 7x - 3x - 21$
$= x(x + 7) - 2(x + 7)$
$= (x - 3)(x + 7)$
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