Find the truth set of the equation x 2 = 3(2x + 9)

Correct Answer is : {x : x = -3, x = 9}

Correct Answer is : {x : x = -3, x = 9}

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WAEC Mathematics 2014 Paper

Question : 9

Total: 49

Find the truth set of the equation x² = 3(2x + 9)

Solution:

Concept:

Solving a quadratic equation by expanding, rearranging, and factoring.

Explanation:

Start with

x^2 = 3(2x + 9)

Expand the right side:

x^2 = 6x + 27

Bring all terms to one side:

x^2 - 6x - 27 = 0

Factor the quadratic:

(x - 9)(x + 3) = 0

Set each factor equal to zero:

x - 9 = 0

x + 3 = 0

Solve:

x = 9

x = -3

Answer:

\{x : x = -3, x = 9\}

Option D.

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