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Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 decade ago

Identify the number that needs to be added to both sides of the equation x2 + 4x = 96 to complete the square.?

Identify the number that needs to be added to both sides of the equation x2 + 4x = 96 to complete the square.

1. 2

2. 16

3. 4

4. –4

11 Answers

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  • 1 decade ago
    Favorite Answer

    Add 4.

    Dear, I can tell you the exact way to make ANY quadratic a perfect square.

    Here goes the steps for a quadratic equation ax^2+bx+c=0

    1. Make the coefficient of x^2 equal to 1. This is done by taking the coefficent 'a' common from the whole quadratic.

    2. Now add and subtract the square of half the coefficient of x i.e (b/2)^2

    3. You can then guess it out yourself then the perfect square.

    For your question:

    Consider x^2 + 4x

    The coefficient of x^2 is already equal to 1 so no worries.

    Now add and subtract by (4/2)^2 which is equal to 4.

    Hey, the second step is also called as "add the square of half the coefficient of x both sides of the equation" because when you subtract the required number it will become positive when it goes to the other side.

    For more tips n tricks you can always contact me.

  • 1 decade ago

    X^2+4x+4=96+4

    (x+2)^2=10^2

  • Anonymous
    1 decade ago

    4

  • 1 decade ago

    4

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  • DWRead
    Lv 7
    1 decade ago

    x² + 4x = 96

    Take the coefficient of the x term

    (+4)

    divide by two

    (+4/2)

    and square the result

    (+4/2)²

    This reduces to 4, so the answer is #3. But I never reduce it completely, (a) because it would have to be undone in the next steps, (b) you might forget which sign to use.

    For example:

    x² - 4x = 0

    To complete the square, you add (-4/2)² to both sides. That can be reduced to 4, but then you lose the minus sign that you need later. Better to use (-2)²:

    x² - 4x + (-2)² = 0 + (-2)²

    (x-2)² = 4

  • Anonymous
    1 decade ago

    When you are completing the square, the number you add to the function is (b/2)^2

    In this case b=4

    (4/2)^2=4

    Therefore your answer if choice 3

  • Como
    Lv 7
    1 decade ago

    (x² + 4x + 4) = 100

    (x + 2)² = 100

    x + 2 = ± 10

    x = 8 , x = - 12

    OPTION 3

  • Anonymous
    1 decade ago

    the answer is 4.

    then the lefh hand side will be x^2+4x+4 = (x+2)^2

    and the right hand side will be 100 = 10^2.

  • Anonymous
    1 decade ago

    x2+4x=96

    since

    a2+b2+2ab=(a+b)2

    so

    (x)2+2(x)(2)+(2)2=96+(2)2

    (x+2)2=96+4

    (x+2)2=100

    taking square root

    x+2=10

    x=10-2

    x=8

    hey its the rite answer why ur choices didnt include this answer

  • 1 decade ago

    # 2 (16)

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