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If 10x + 10y + 16x^2 + 25y^2 = 10 + Z, what is the value of x + y?
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18 Mar 2016, 00:13
18 Mar 2016, 00:13
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If \(10x + 10y + 16x^2 + 25y^2 = 10 + z\), what is the value of x + y?
(1) \(z = (4x)^2 + (5y)^2\)
(2) \(x = 1\)
(1) \(z = (4x)^2 + (5y)^2\)
(2) \(x = 1\)
If 10x + 10y + 16x^2 + 25y^2 = 10 + Z, what is the value of x + y?
[#permalink]
18 Mar 2016, 01:50
18 Mar 2016, 01:50
St1: z = \(16x^2 + 25y^2\) --> 10(x + y) = 10 --> x + y = 1. Sufficient
St2: Clearly insufficient as we do not know the value of y and z
Answer: A
St2: Clearly insufficient as we do not know the value of y and z
Answer: A
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 10133
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: If 10x + 10y + 16x^2 + 25y^2 = 10 + Z, what is the value of x + y?
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19 Mar 2016, 23:19
19 Mar 2016, 23:19
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Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
If 10x+10y+16x^2+25y^2=10+z , what is the value of x + y?
(1) z=(4x)^2+(5y)^2
(2) x=1
When you modify the original condition and the question, x+y=(10+z-16x^2-25y^2)/10 is derived. For 1), x+y=1 is derived from z=16x^2+25y^2, which is sufficient. The answer is A.
Once we modify the original condition and the question according to the variable approach method 1, we can solve approximately 30% of DS questions.
If 10x+10y+16x^2+25y^2=10+z , what is the value of x + y?
(1) z=(4x)^2+(5y)^2
(2) x=1
When you modify the original condition and the question, x+y=(10+z-16x^2-25y^2)/10 is derived. For 1), x+y=1 is derived from z=16x^2+25y^2, which is sufficient. The answer is A.
Once we modify the original condition and the question according to the variable approach method 1, we can solve approximately 30% of DS questions.
