Question

The image of the point (3, 8) in the line x + 3y = 7 is

• A. (1, -4)
• B. (1, 4)
• C. (-1, -4)
• D. None of these

Answer 1

Answer: (C)

(-1, -4)

Answer 2

Let P′ the image of P in the line x + 3y = 7.

Then x + 3y = 7 will be perpendicular bisector of PP′.

Equation of PP′ is y – 8 = 3(x-3)

⇒ 3x –y – 1 = 0.

On sol v ing 3x-y-1 = 0 and x + 3y = 7,we get the

coordinates of M as (1, 2). Since M is mid point of PP’,

coordinates of P′ are (-1, -4)