- AI
- BIII
- CIV
- DII
Step-by-Step Solution
In quadrant I both a and b are positive. Changing the sign of the abscissa gives a negative abscissa with a positive ordinate, which is quadrant II.
Answer: D) II
The point P(a, b) lies in quadrant I. In which quadrant does the point Q(−a, b) lie?
Class 9Coordinate GeometryCoordinate Geometry
Key idea: Special points
- **Origin**: (0, 0).
- **On -axis**: , so the form is (a, 0). Examples: (3, 0), (−5, 0).
- **On -axis**: , so the form is (0, b). Examples: (0, 7), (0, −2).
- **First-quadrant point**: both positive.
- **Third-quadrant point**: both negative.
Knowing which axis or quadrant a point belongs to is a quick check that you've plotted it correctly.
- **On -axis**: , so the form is (a, 0). Examples: (3, 0), (−5, 0).
- **On -axis**: , so the form is (0, b). Examples: (0, 7), (0, −2).
- **First-quadrant point**: both positive.
- **Third-quadrant point**: both negative.
Knowing which axis or quadrant a point belongs to is a quick check that you've plotted it correctly.
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