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In the equation x^2 + bx + 12 = 0, x is a variable and b is
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29 Jan 2014, 02:14
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The Official Guide For GMAT® Quantitative Review, 2ND EditionIn the equation x^2 + bx + 12 = 0, x is a variable and b is a constant. What is the value of b ? (1) x  3 is a factor of x^2 + bx + 12. (2) 4 is a root of the equation x^2 + bx + 12 = 0. Data Sufficiency Question: 62 Category: Algebra First and seconddegree equations Page: 157 Difficulty: 600 GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition  Quantitative Questions ProjectEach week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution. We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation. Thank you!
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Re: In the equation x^2 + bx + 12 = 0, x is a variable and b is
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29 Jan 2014, 02:15



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Re: In the equation x^2 + bx + 12 = 0, x is a variable and b is
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29 Jan 2014, 02:51
From S1:x3 is a factor of the given equation=>x=3 is a root of the equation.Putting x=3 in the eq x^2+bx+12 we can get the value of b.Hence sufficient. From S2:4 is a root of the equation=>Putting x=4 in the equation we can find out b.Sufficient. Ans.D



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Re: In the equation x^2 + bx + 12 = 0, x is a variable and b is
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16 Jul 2017, 13:25
In the equation x^2 + bx + 12 = 0, x is a variable and b is a constant. What is the value of b ?(1)\(x  3\) is a factor of \(x^2 + bx + 12\)as \((x3)\) is one of the factor, this means that \(x = 3\) is one of the roots of the equation \(x^2 + bx + 12\) In order to get 12 = we only have one value after 3 and that is 4 as \(4 * 3 = 12\) Hence, \(bx = 4x + 3x = 7x\), value of \(b = 7\) Hence, (1) ===== is SUFFICIENT(2) 4 is a root of the equation \(x^2 + bx + 12 = 0\)As 4 is one of the roots, the other root will be 3 Hence, \(bx = 4x + 3x = 7x\), value of \(b = 7\) Hence, (2) ===== is SUFFICIENTHence, Answer is DDid you like the answer? 1 Kudos Please
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Re: In the equation x^2 + bx + 12 = 0, x is a variable and b is
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03 Jan 2018, 09:10
Bunuel wrote: The Official Guide For GMAT® Quantitative Review, 2ND EditionIn the equation x^2 + bx + 12 = 0, x is a variable and b is a constant. What is the value of b ? (1) x  3 is a factor of x^2 + bx + 12. (2) 4 is a root of the equation x^2 + bx + 12 = 0. Data Sufficiency Question: 62 Category: Algebra First and seconddegree equations Page: 157 Difficulty: 600 GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition  Quantitative Questions ProjectEach week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution. We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation. Thank you! From st 1: x  3 is a factor of x^2 + bx + 12 x  3 = 0 or x = 3 Put x = 3 in x^2 + bx + 12 = 0. This gives us x = 7 > Sufficient From st 2: 4 is a root of the equation x^2 + bx + 12 = 0 means x = 4, Put x = 4 in x^2 + bx + 12 = 0. This gives us x = 7 > Sufficient (D)
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Re: In the equation x^2 + bx + 12 = 0, x is a variable and b is
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10 Jun 2018, 11:13
Bunuel wrote: SOLUTION
In the equation x^2 + bx + 12 = 0, x is a variable and b is a constant. What is the value of b ?[b][/b]
(1) x3 is a factor of x^2 + bx + 12 > simply means that x=3 is a root of x^2+bx+12=0 (if x3 is a factor of x^2+bx+12 then x^2+bx+12=(x3)(xk)=0, for some k, so x=3 is on of the roots of the equation) > substitute x=3: 3^2+3b+12=0 > b=7. Sufficient.
(2) 4 is a root of x^2 + bx + 12 = 0 > the same here, substitute x=4: 4^2+4b+12=0 > b=7. Sufficient.
Answer: D. I'm a bit confused as to the term 'root' and specifically the phrase '4 is a root of x^2' here. How should this be interpreted? I thought of it as the factor of 12 (i.e. 4x = 12). Thanks ahead of time.



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Re: In the equation x^2 + bx + 12 = 0, x is a variable and b is
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10 Jun 2018, 11:18
energy2pe wrote: Bunuel wrote: SOLUTION
In the equation x^2 + bx + 12 = 0, x is a variable and b is a constant. What is the value of b ?[b][/b]
(1) x3 is a factor of x^2 + bx + 12 > simply means that x=3 is a root of x^2+bx+12=0 (if x3 is a factor of x^2+bx+12 then x^2+bx+12=(x3)(xk)=0, for some k, so x=3 is on of the roots of the equation) > substitute x=3: 3^2+3b+12=0 > b=7. Sufficient.
(2) 4 is a root of x^2 + bx + 12 = 0 > the same here, substitute x=4: 4^2+4b+12=0 > b=7. Sufficient.
Answer: D. I'm a bit confused as to the term 'root' and specifically the phrase '4 is a root of x^2' here. How should this be interpreted? I thought of it as the factor of 12 (i.e. 4x = 12). Thanks ahead of time. "root" is the same as "solution" We can say "x = 3 is a solution to the equation 2x = 6" or we can say "3 is a root of the equation 2x = 6" Cheers, Brent
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Re: In the equation x^2 + bx + 12 = 0, x is a variable and b is
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10 Jun 2018, 11:32
GMATPrepNow wrote: energy2pe wrote: Bunuel wrote: SOLUTION
In the equation x^2 + bx + 12 = 0, x is a variable and b is a constant. What is the value of b ?[b][/b]
(1) x3 is a factor of x^2 + bx + 12 > simply means that x=3 is a root of x^2+bx+12=0 (if x3 is a factor of x^2+bx+12 then x^2+bx+12=(x3)(xk)=0, for some k, so x=3 is on of the roots of the equation) > substitute x=3: 3^2+3b+12=0 > b=7. Sufficient.
(2) 4 is a root of x^2 + bx + 12 = 0 > the same here, substitute x=4: 4^2+4b+12=0 > b=7. Sufficient.
Answer: D. I'm a bit confused as to the term 'root' and specifically the phrase '4 is a root of x^2' here. How should this be interpreted? I thought of it as the factor of 12 (i.e. 4x = 12). Thanks ahead of time. "root" is the same as "solution" We can say "x = 3 is a solution to the equation 2x = 6" or we can say "3 is a root of the equation 2x = 6" Cheers, Brent Ahh, got it. Thanks. Fan of the youtube channel btwI've subscribed : )




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