3
QuizMultiple Choice

The Quadratic Formula — Quiz

Question 3 • Advanced Algebra: Concepts and Connections

Using the quadratic formula to solve x squared plus 20 is equal to 2 x , what are the values of x ?

Answer
A
1 plus or minus square root of 21 i
B
1 plus or minus square root of 19 i
C
1 plus or minus 2 square root of 19 i
D
negative 1 plus or minus square root of 19 i

Explanation

Rewrite the equation in standard form: x² − 2x + 20 = 0. Using the quadratic formula, the discriminant is (−2)² − 4(1)(20) = −76, so the roots are [2 ± √(−76)]/2 = 1 ± √19 i. Therefore, the values are 1 plus or minus square root of 19 i, choice D.

AI-written and checked against the verified answer.

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