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Re: For which of the following values does ax^2 + 2x + c =0 not [#permalink]
quadratic equation ax^2 +bx +c =0 doesn't have real root when b^2-4ac <0

for the equation in question, b =2 so 4 -4ac <0>4<4ac>ac>1
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Re: For which of the following values does ax^2 + 2x + c =0 not [#permalink]
nervousgmat wrote:
For which of the following values does ax^2 + 2x + c =0 not have any real root?
A) ac>1
B) ac<1>-1
E) it cannot be determined from the information given

I have an OA, so please provide your explanations!



4 - 4ac < 0 is condition for imaginary roots
or 1 - ac < 0
or 1 < ac

Hence A
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Re: For which of the following values does ax^2 + 2x + c =0 not [#permalink]
techjanson wrote:
nervousgmat wrote:
For which of the following values does ax^2 + 2x + c =0 not have any real root?
A) ac>1
B) ac<1>-1
E) it cannot be determined from the information given

I have an OA, so please provide your explanations!



4 - 4ac < 0 is condition for imaginary roots
or 1 - ac < 0
or 1 < ac

Hence A


Same explanation, same answer. :)

Using the quadratic formula root test.
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Re: For which of the following values does ax^2 + 2x + c =0 not [#permalink]
Thanks, guys for your replies!
I had no idea about the quadratic formula root test. Never studied this in my life!

The OA is A!



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Re: For which of the following values does ax^2 + 2x + c =0 not [#permalink]
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Re: For which of the following values does ax^2 + 2x + c =0 not [#permalink]
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