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If 2x^2 - y^2 = 2xy, then (x+y)^2 =

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If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

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New post 10 May 2010, 16:45
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If 2x^2 - y^2 = 2xy, then (x+y)^2 =

A. x^2
B. 3x^2
C. 4xy
D. 2y^2
E. -y^2

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If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

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New post 11 Nov 2010, 23:21
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Re: please help solve this for me  [#permalink]

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New post 10 May 2010, 16:50
2
Its B

2x^2 -y^2 = 2xy
2x^2 = 2xy + y^2

Add x^2 on both sides we get

2x^2 +x^2 = x^2 +y^2 +2xy
3x^2 = (x+y)^2
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If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

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New post 10 May 2010, 16:53
2
5
bakfed wrote:
If 2x^2 - y^2 = 2xy, then (x+y)^2 =

A. x^2
B. 3x^2
C. 4xy
D. 2y^2
E. -y^2

OA


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Re: please help solve this for me  [#permalink]

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New post 18 May 2010, 08:17
1
bakfed wrote:
If 2x^2 - y^2 = 2xy, then (x+y)^2 =

A. x^2
B. 3x^2
C. 4xy
D. 2y^2
E. -y^2

OA

here we have to find the value of x^2 +y^2 +2xy in which 2xy
=2x^2 -y^2 (given ) hence ans is 3x^2.
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Re: If 2x^2 –y^2 = 2xy  [#permalink]

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New post 12 Nov 2010, 13:46
2x^2 –y^2 = 2xy
2x^2 = 2xy+y^2

3x^2 = x^2 + 2xy+y^2 (adding x^2 on both sides)

3x^2 = (x+y)^2


Answer:- B
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Re: If 2x^2 –y^2 = 2xy  [#permalink]

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New post 12 Nov 2010, 16:30
2x\(^2\)-y\(^2\)=2xy

(x+y)\(^2\)= x\(^2\)+2xy+y\(^2\)

replace 2xy by 2x\(^2\)-y\(^2\) and solve

Answer B.
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Re: If 2x^2 –y^2 = 2xy  [#permalink]

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New post 29 Dec 2010, 12:08
Sarang wrote:
2x^2 –y^2 = 2xy
2x^2 = 2xy+y^2

3x^2 = x^2 + 2xy+y^2 (adding x^2 on both sides)

3x^2 = (x+y)^2


Answer:- B


i didn't understand this pls explain
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Re: If 2x^2 –y^2 = 2xy  [#permalink]

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New post 29 Dec 2010, 12:33
rahul321 wrote:
Sarang wrote:
2x^2 –y^2 = 2xy
2x^2 = 2xy+y^2

3x^2 = x^2 + 2xy+y^2 (adding x^2 on both sides)

3x^2 = (x+y)^2


Answer:- B


i didn't understand this pls explain


Given: \(2x^2-y^2=2xy\) --> rearrange: \(2x^2=2xy+y^2\) --> add \(x^2\) to both parts of the equation: \(2x^2+x^2=x^2+2xy+y^2\) --> \(3x^2=(x+y)^2\).

Hope it's clear.
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If 2x^2 –y^2 = 2xy, then (x+y)^2=  [#permalink]

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New post 17 Jul 2014, 01:42
\(2x^2 – y^2 = 2xy\)

so, \(y^2 = 2x^2 - 2xy\) ............ (1)

\((x+y)^2 = x^2 + 2xy + y^2\)

Placing value of \(y^2\) from (1)

\(= x^2 + 2xy + 2x^2 - 2xy\)

\(= 3x^2\)

Answer = B
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Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

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New post 24 Mar 2017, 04:30
Quite straight forward question

step 1:
(x+Y)^2 = X^2 +2xy + y^2

step 2:
now substitute 2xy from the equation.

(x+Y)^2 = X^2 +2x^2-y^2+y^2.

-y^2 and Y^2 cancels out

we are left with x^2+2X^2= 3X^2 Hence B.
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Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

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New post 27 Mar 2017, 16:22
1
bakfed wrote:
If 2x^2 - y^2 = 2xy, then (x+y)^2 =

A. x^2
B. 3x^2
C. 4xy
D. 2y^2
E. -y^2


We see that we are looking for the value of (x + y)^2 = x^2 + y^2 + 2xy.

We also see that 2x^2 - y^2 = 2xy; thus we can substitute for 2xy and we have:

x^2 + y^2 + 2x^2 - y^2 = 3x^2

Answer: B
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Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 =  [#permalink]

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New post 24 Oct 2018, 06:36
Given: 2xy=2x2−y22xy=2x2−y2.

(x+y)2=x2+2xy+y2(x+y)2=x2+2xy+y2
substitute 2xy2xy
(x+y)2=x2+(2x2−y2)+y2=3x2(x+y)2=x2+(2x2−y2)+y2=3x2.

B.
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Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 = &nbs [#permalink] 24 Oct 2018, 06:36
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