MCQ
The factors of $x^2-9$ is:
- A$(x - 3) (x - 3)$
- ✓$(x + 3) ( x + 3)$
- C$(x + 3) (x - 3)$
- D$(x - 3) (x + 9)$
✓
Answer
Correct option: B.
$(x + 3) ( x + 3)$
$x^2-9$
$=x^2-3^2$
Using identity $\mathrm{a}^2-\mathrm{b}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$
$=(x+3)(x-3)$
$=x^2-3^2$
Using identity $\mathrm{a}^2-\mathrm{b}^2=(\mathrm{a}+\mathrm{b})(\mathrm{a}-\mathrm{b})$
$=(x+3)(x-3)$
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