Mathematics
If the point P(a, b) is reflected in the origin to P'(7, -13), then the value of (a - b) is :
20
6
-20
-6
Answer
Given,
Co-ordinates of point P = (a, b) and P' = (7, -13).
We know that,
On reflecting in origin the sign of both x and y co-ordinate changes.
∴ (a, b) ⇒ (-a, -b)
Given,
P(a, b) is reflected in the origin to P'(7, -13)
∴ (7, -13) = (-a, -b)
⇒ -a = 7 and -b = -13
⇒ a = -7 and b = 13.
∴ a - b = -7 - 13 = -20.
Hence, Option 3 is the correct option.
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