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cbAuroraIn Group Title

I'm trying to solve 2x^2+11x-21 by quadratic formula. Factoring gives 3/2, -7, but by the formula (which should always work), I get: (-11/4)+/-((22/4)(42)^(1/2)). Can anyone help me spot my stupid error?

  • 2 years ago
  • 2 years ago

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  1. lalaly Group Title
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    are u still there?

    • 2 years ago
  2. mominanisar Group Title
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    factoring gives 3/2, -7, the quadratic formula is x=(-b±sqrt(b^2-4ac))/2a from your equation a=2,b=11,c=-21 put values in formula x=(-11±sqrt(121-(168)))/2x2 x=(-11±sqrt(289))/4 x=(-11±17)/4. x=3/2, -7

    • 2 years ago
  3. jhonyy9 Group Title
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    so if factoring this is right (2x-3)(x+7)=2x2+11x-21 so than your got solutions x=3/2 and x=-7 is right,correct sure always

    • 2 years ago
  4. jhonyy9 Group Title
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    mominanisar ATTENTION in this calcules are some errore because inside squarroot there not is minus 168 correct,right is plus 168 and in thgis way will get these correct factorized resultes

    • 2 years ago
  5. jhonyy9 Group Title
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    check it newly please

    • 2 years ago
  6. mominanisar Group Title
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    i am seriously sorry actually this step is likex=(-11±sqrt(121-(168)))/2x2 new onex=(-11±sqrt(121-(-168)))/2x2 because 'c' is minus

    • 2 years ago
  7. mominanisar Group Title
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    it is a typing mistake by me

    • 2 years ago
  8. cbAuroraIn Group Title
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    Thanks!

    • 2 years ago
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