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

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bakfed
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If 2x^2 - y^2 = 2xy, then (x+y)^2 = [#permalink] New post   10 May 2010, 17:45
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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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B
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If 2x^2 - y^2 = 2xy, then (x+y)^2 = [#permalink] New post   10 May 2010, 17:53
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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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B


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If 2x^2 - y^2 = 2xy, then (x+y)^2 = [#permalink] New post   12 Nov 2010, 00:21
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monirjewel 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


Given: \(2xy=2x^2-y^2\).

\((x+y)^2 =x^2+2xy+y^2\) --> substitute \(2xy\) --> \((x+y)^2 =x^2+(2x^2 - y^2)+y^2=3x^2\).

Answer: B.
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Re: please help solve this for me [#permalink] New post   10 May 2010, 17:50
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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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Re: please help solve this for me [#permalink] New post   18 May 2010, 09:17
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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
Show Spoiler
B

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] New post   12 Nov 2010, 14:46
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] New post   12 Nov 2010, 17:30
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] New post   29 Dec 2010, 13:08
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] New post   29 Dec 2010, 13:33
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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] New post   17 Jul 2014, 02:42
\(2x^2 – y^2 = 2xy\)

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] New post   24 Mar 2017, 05:30
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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] New post   27 Mar 2017, 17:22
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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] New post   24 Oct 2018, 07:36
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 = [#permalink] New post   15 Oct 2020, 02:37
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\(2x^2 - y^2 = 2xy\) ----------Equation (1)

=> \((x + y)^2 = x^2 + y^2 + 2xy\) ----------Equation (2)

Multiply Equation (1) by (-1),

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

=> \(- 2x^2 + y^2 + 2xy = 0\)

=> \(- 3x^2 + x^2 + y^2 + 2xy = 0 \)

From ----------Equation (2),

=> \(- 3x^2 + (x + y)^2 = 0 \)

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

Answer B
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Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 = [#permalink] New post   24 Oct 2020, 11:40
Given: \(2x^2 - y^2 = 2xy\)

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

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

\(= 3x^2\\
\)

Answer is B.
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Re: If 2x^2 - y^2 = 2xy, then (x+y)^2 = [#permalink] New post   08 Nov 2021, 07:58
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