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If a > 0 and b < 0, which of the following statements are t [#permalink]
 15 Jun 2017, 07:37
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Question Stats:
62% (01:31) correct
37% (01:35) wrong based on 24 sessions
If a > 0 and b < 0, which of the following statements are true about the values of x that solve the equation \(x^2\) – ax + b = 0? Indicate all such statements. ❑ They have opposite signs. ❑ Their sum is greater than zero. ❑ Their product equals –b.
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Re: If a > 0 and b < 0, which of the following statements are t [#permalink]
24 Sep 2017, 08:41
My strategy has been to write an example of second degree equation that is easy to solve as x^2-x-4 = 0, where a = 1 and b = -4. This is easily factorized as (x-2)(x+1) = 0 so that the solutions are 2 and -1. Thus, we can screening our choices:
❑ They have opposite signs: 2 and -1 have opposite signs -> CORRECT
❑ Their sum is greater than zero: 2 + (-1) = 1 >0 -> CORRECT
❑ Their product equals –b: 2*(-1) = -2 while b = -4 -> WRONG
Answers are A and B!
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Re: If a > 0 and b < 0, which of the following statements are t [#permalink]
21 Aug 2018, 03:09
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for equation ax^2+bx+c = 0
sum of roots = -b/a
product of roots = c/a
In case of this question:
x^2-ax+b = 0
sum of roots = a (since a> 0 , option b is correct)
product of roots = b (option c incorrect)
product of roots = b and since b is less than 0 , therefore both roots should be of opposite sign (option a correct)
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Re: If a > 0 and b < 0, which of the following statements are t
[#permalink]
21 Aug 2018, 03:09
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