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anonymous

  • one year ago

-2x² - 7 = 4x Where are a, b, and c in this equation? How do I solve this with the quadratic equation?

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  1. Jamierox4ev3r
    • one year ago
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    remember, a standard quadratic equation is always in this form: \(a^{2}x+bx+c\) so you're going to need to manipulate this equation to set it to this formula

  2. anonymous
    • one year ago
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    Is a 2? Is b 4? Is C 7?

  3. butterflydreamer
    • one year ago
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    we have this equation: -2x² - 7 = 4x We need to rearrange it so that the x² part is positive. Therefore take the "-2x² - 7" to the other side of the equals sign and we get: -2x² - 7 = 4x 0 = 2x² + 4x +7 Standard form is : ax² + bx + c = 0 Therefore match it up with your equation and we get: a = 2, b = 4 , c = 7 Which you said.. so you're correct ^_^!

  4. anonymous
    • one year ago
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    How do I solve this?

  5. anonymous
    • one year ago
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    use this formula\[x=\frac{ -b \pm \sqrt{b^2-4ac} }{ 2a }\]

  6. butterflydreamer
    • one year ago
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    yeah use the quadratic formula (as stated by surjithayer) to solve for x :)

  7. anonymous
    • one year ago
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    1.58?

  8. butterflydreamer
    • one year ago
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    not quite we know a = 2, b = 4 and c = 7 plug these values into the quadratic formula: |dw:1433428335720:dw|

  9. butterflydreamer
    • one year ago
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    note: we cannot square root a negative number. Therefore, there will be no solution... What i mean by this is that in this part here: |dw:1433428482052:dw| And we can't square root -40. Therefore x will have no solution

  10. anonymous
    • one year ago
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    WHAT?!

  11. anonymous
    • one year ago
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    I thought that when the numerator says "\[\pm\]", you were supposed to change the number to a positive whenever you square rooted it.

  12. butterflydreamer
    • one year ago
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    hmm.. the plus and minus sign, means that you can get TWO solutions... for x. You want to concentrate on what is happening INSIDE the square root sign: |dw:1433430575846:dw| plug it into the calculator and tell me if you get an answer :)

  13. butterflydreamer
    • one year ago
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    you should get a math error. Why? Because we can't square root a negative number.

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