Multiple Choice Question (MCQ)

What is the solution set to the equation 4+x^2=2x^2-5 ?

  1. ×

    \{x:x=3\}

  2. ×

    \{x:x=-3\}

  3. \{x:x=\pm3\}

  4. ×

    \{x:x=-1\}

  5. ×

    \{x:x=1\}

Collected in the board: Algebraic equation

Steven Zheng posted 3 years ago

Answer

  1. A solution set is the set of variables that makes the equation true. For a quadratic equation, it has either 2 duplicate roots(1 solution) or distinct roots.

    Solving the equation gives

    4+x^2=2x^2-5

    x^2=9

    Taking the square roots

    x=\pm3

    It turns out the equation has two distinct solutions. So the solution set of the equation is \{x:x=\pm3\} .

    C is the correct choice.

Steven Zheng posted 3 years ago

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