Find the radius of the circle 2x\(^2\) - 4x + 2y\(^2\) - 6y -2 = 0.

  • A 17/4
  • B 17/2
  • C 17/√2
  • D √17/2 
waec 2021furthermathematics

The correct answer is C. 17/√2

2x\(^3\) - 4x + 2y\(^2\) - 6y - 2 = 0

Divide through by 2: x\(^2\) - 2x + y\(^2\) -3y -1 = 0

x\(^2\) -2x + y\(^2\) - 3y = 1

x\(^2\) -2x + 1 + y\(^2\) - 3y + 9/4

= 1+ 1 + 9/4

= (x- 1)\(^2\) (y - 3/2)\(^2\)

= √[17/4]

r = √17/2

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