Solve the equation by completing the square x^2-18x+58=0. is it a. x= -9+-√23 b. x= -9+-√139 c. x= 9+-√139 d. x= 9+-√23

To complete the square we add a constant (23) so that the constant on the left is (18/2)² = 81.
   x² -18x +58 +23 = 23
   (x -9)² = 23 . . . . . . . . . . . rewrite the left side as a square
   x -9 = ±√23 . . . . . . . . . . . take the square root
   x = 9 ±√23 . . . . . . . . . . . .add 9

The answer corresponds to selection ...
   D. x = 9 ±√23

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Step-by-step explanation: