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3 votes
Solve this quadratic equation by completing the square.
x2 + 6x = 18

User LCJ
by
7.8k points

1 Answer

7 votes

Answer:

x=3sqrt3-3; x=-3sqrt3-3

Explanation:

solve for a, 2ax=6x; a=3:

x^2+6x+3^2=18+3^2

Simplify, 18+3^2=27:

x^2+6x+3^2=27

Complete square: (x+3)^2=27

Two answers: x+3=sqrt27; x+3=-sqrt27

Therefore, x=3sqrt3-3; x=-3sqrt3-3

User Azalia
by
9.0k points

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