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26 Jul 2018, 00:09
Kudos
Bookmarks
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
70% (01:05) correct
30%
(00:58)
wrong
based on 164
sessions
History
Date
Time
Result
Not Attempted Yet
What is the value of x?
(1) x^2 + 4x = –8x – 35
(2) x^2 + 3x = –7x – 25
(1) x^2 + 4x = –8x – 35
(2) x^2 + 3x = –7x – 25
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
26 Jul 2018, 00:22
Kudos
Bookmarks
Bunuel
OA: B
Statement 1 :\(x^2 + 4x = –8x – 35\)
\(x^2 + 12x+35=0\)
\(x^2 + 7x+5x+7*5=0\)
\((x+7)(x+5)=0\)
\(x=-5,-7\)
Two different value of \(x\) , hence Statement 1 alone is not sufficient.
Statement 2:\(x^2 + 3x = –7x – 25\)
\(x^2 + 10x+25 =0\)
\(x^2 + 5x+5x+5*5 =0\)
\((x+5)(x+5)=0\)
\(x=-5\)
1 unique value of \(x\) , hence Statement 2 alone is sufficient.
26 Jul 2018, 00:23
Kudos
Bookmarks
What is the value of x?
A quadratic equation has almost always two roots. if the equation is in the form of \(a^2-2ab+b^2\) or \(a^2+2ab+b^2\), when both the roots are same, the value will be one...
(1) x^2 + 4x = –8x – 35
\(x^2+12x+35=0\)...Had this been \(x^2+12x+36=0\), we would have had only one value as \(x^2+12x+36=0........x^2+2*1*6x+6^2=0\)
but now there will be two values
insuff
(2) x^2 + 3x = –7x – 25
\(x^2+10x+25=0............x^2+2*1*5x+5^2=0..........(x+5)^2=0\)
hence x is -5
sufficient
B
A quadratic equation has almost always two roots. if the equation is in the form of \(a^2-2ab+b^2\) or \(a^2+2ab+b^2\), when both the roots are same, the value will be one...
(1) x^2 + 4x = –8x – 35
\(x^2+12x+35=0\)...Had this been \(x^2+12x+36=0\), we would have had only one value as \(x^2+12x+36=0........x^2+2*1*6x+6^2=0\)
but now there will be two values
insuff
(2) x^2 + 3x = –7x – 25
\(x^2+10x+25=0............x^2+2*1*5x+5^2=0..........(x+5)^2=0\)
hence x is -5
sufficient
B
