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(x + 7) is a factor in x^2  mx  56. What is the value of m
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Updated on: 05 Dec 2012, 07:03
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(x + 7) is a factor in x^2  mx  56. What is the value of m? A. 1 B. 8 C. 14 D. 15 E. 16
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Originally posted by Archit143 on 05 Dec 2012, 07:00.
Last edited by Bunuel on 05 Dec 2012, 07:03, edited 1 time in total.
Edited the question.



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Re: (x + 7) is a factor in x^2  mx  56. What is the value of m
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05 Dec 2012, 10:01
Given the fact that \((x+7)\) is the factor of the equation, so it claerly means that one value of x=7; the other we don't know and we don't have to. The equation can be written in factor form as: \((x+7)*(x+a)\) where a is the other value of x. On putting the value of x=7 in the equation, \(x^2mx56=0\) we get: \(49+7m56=0\) \(7=7m\) \(m=1\) +1 A.
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Re: (x + 7) is a factor in x^2  mx  56. What is the value of m
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05 Dec 2012, 23:20
thanks marcab just wanted to be sure of my approach



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Re: (x + 7) is a factor in x^2  mx  56. What is the value of m
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15 Jan 2015, 02:53
I solved the second degree equation and found it like this:
x^2  mx  56 = 0 (x8)(x+7) = 0 x=8 or x= 7
Substituting both values for x in the equation we find: x^2  mx  56 => (7)^2  m(7)  56 => 49  56 + 7m => 49 + 56 = 7m => 7 = 7m => m = 1
And with 8, using a similar process we end up with: 6456=8m 8=8m m=1
Ao, ANS A



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Re: (x + 7) is a factor in x^2  mx  56. What is the value of m
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28 May 2016, 22:37
l got the same answer. lt's not stated in the question stem that x^2  mx  56 = 0. Based on what information do we know (x^2  mx  56) equals to zero? Could someone please clarify? Regards, Curious mind.
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Re: (x + 7) is a factor in x^2  mx  56. What is the value of m
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28 May 2016, 23:14
ranaazad wrote: l got the same answer. lt's not stated in the question stem that x^2  mx  56 = 0. Based on what information do we know (x^2  mx  56) equals to zero? Could someone please clarify? Regards, Curious mind. Hi, x^2mx56 can be any value depending on value of x..... this equation is that of PARABOLA, so you will get a parabola when you draw a graph of it... Just remember for GMAT that but when we factor or find roots, we work for ONLY those values of x at which the equation gives us a 0 value.. That is why when we are factoring the equation here we take the equation to be equal to 0... so If I tell you the speed of something is dependent on x^215x+56 and then ask you speed at say 9h second, substitute x as 9 and find the answer.. But if I ask you at what values will the speed be 0, put the equation as 0 and find values of x..
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Re: (x + 7) is a factor in x^2  mx  56. What is the value of m
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28 May 2016, 23:44
Archit143 wrote: (x + 7) is a factor in x^2  mx  56. What is the value of m?
A. 1 B. 8 C. 14 D. 15 E. 16 If (x+7) is a factor of expression x^2  mx  56, then if we substitute x = 7, in the given expression, the value of expression will be zero. So, (7)^2  (m)(7)  56 = 0 49+7m56 = 0 7m7=0 m=1 A is the answer



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Re: (x + 7) is a factor in x^2  mx  56. What is the value of m
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10 Jun 2017, 07:13
Archit143 wrote: (x + 7) is a factor in x^2  mx  56. What is the value of m?
A. 1 B. 8 C. 14 D. 15 E. 16 Since (x + 7) is a factor of x^2  mx  56, we know that x = 7 will satisfy the equation x^2  mx  56 = 0; therefore, we can substitute 7 for x and we have: (7)^2  7m  56 = 0 49  7m = 56 7m = 7 m = 1 Answer: A
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Re: (x + 7) is a factor in x^2  mx  56. What is the value of m
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10 Jun 2017, 11:41
Imo A Substitute the value x=7 We get m=1 Sent from my ONE E1003 using GMAT Club Forum mobile app



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