Mathematics
If the point P(a, b) is first reflected in the x-axis and then reflected in the origin to the point P"(-8, -2), then the value of (a - 2b) is :
-12
12
10
-10
Reflection
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Answer
Given, point P(a, b).
On reflection in x-axis, the sign of y-coordinate changes.
(a, b) ⇒ (a, -b)
On reflection in origin, the sign of x-coordinate and y-coordinate changes.
(a, -b) ⇒ (-a, b)
Given, final point P'(-8, -2)
∴ (-a, b) = (-8, -2)
⇒ -a = -8 and b = -2
⇒ a = 8 and b = -2
⇒ a - 2b = 8 - 2(-2)
⇒ 8 + 4
⇒ 12.
Hence, Option 2 is the correct option.
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