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If 0.5(y − x) = −1 and x2 − y2 = 24, what is the sum of x
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17 Mar 2018, 07:28
17 Mar 2018, 07:28
Expert Reply
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Question Stats:
90% (00:51) correct
10% (02:04) wrong based on 10 sessions
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If 0.5(y − x) = −1 and \(x^2 - y^2 = 24\), what is the sum of x and y ?
A. −48
B. −12
C. 6
D. 12
E. 48
A. −48
B. −12
C. 6
D. 12
E. 48
Drill 2
Question: 6
Page: 497-498
Question: 6
Page: 497-498
Re: If 0.5(y − x) = −1 and x2 − y2 = 24, what is the sum of x
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18 Mar 2018, 07:02
18 Mar 2018, 07:02
1
Expert Reply
Explanation
Know your common quadratics. You are asked for the value of x + y.
Because \(x^2 - y^2 =(x + y)(x - y) = 24\), if the value of (x − y) is found, (x + y) can be figured out.
Manipulate the equation 0.5(y − x) = –1 to get (y − x) = –2.
Multiplying both sides by –1, you get x – y = 2.
Substitute this value into the equation (x + y)(x – y) = 24 and then divide both sides of the equation by 2 to get (x + y) = 12. The answer is choice (D).
Know your common quadratics. You are asked for the value of x + y.
Because \(x^2 - y^2 =(x + y)(x - y) = 24\), if the value of (x − y) is found, (x + y) can be figured out.
Manipulate the equation 0.5(y − x) = –1 to get (y − x) = –2.
Multiplying both sides by –1, you get x – y = 2.
Substitute this value into the equation (x + y)(x – y) = 24 and then divide both sides of the equation by 2 to get (x + y) = 12. The answer is choice (D).
gmatclubot
Re: If 0.5(y − x) = −1 and x2 − y2 = 24, what is the sum of x [#permalink]
18 Mar 2018, 07:02
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