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Use inspection to solve the equation x^2 = 81, the select the complete solution set below.

A. {-9}
B. {9}
C. {-9, 9}
D. There are no real solutions

1 answer

To solve the equation \( x^2 = 81 \) using inspection, we can look for values of \( x \) that, when squared, equal 81.

  1. The square root of 81 is 9.
  2. Therefore, \( x \) can be 9 or -9, since both \( 9^2 = 81 \) and \( (-9)^2 = 81 \).

Hence, the complete solution set is \( {-9, 9} \).

The correct answer is:

C. {-9, 9}