MCQ
Factorised form of $r^2- 10r + 21$ is:
- A$(r - 1)(r - 4)$
- ✓$(r - 7)(r - 3)$
- C$(r - 7)(r + 3)$
- D$(r + 7)(r + 3)$
✓
Answer
Correct option: B.
$(r - 7)(r - 3)$
B. $(r - 7)(r - 3)$
Solution:
We have,
$r^2 - 10r + 21$
$= r^2 - 7r - 3r + 21$
$= r(r - 7) - 3(r - 7)$
$= (r - 7)(r - 3)$
Solution:
We have,
$r^2 - 10r + 21$
$= r^2 - 7r - 3r + 21$
$= r(r - 7) - 3(r - 7)$
$= (r - 7)(r - 3)$
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