X+2y=9 and xy=7,find the value of x^2 +4y^2
Answers
Answered by
7
by squaring first equation we will get (x+2y)^2=81, Now by solving it we will get x^2+4xy+y^2=81
by putting the value of xy(=7) in above equation we will get the required answer.
Thank you :)
by putting the value of xy(=7) in above equation we will get the required answer.
Thank you :)
Answered by
12
sincexy=7
so x=7/y
a/q
x+2y=9
or 7/y+2y=9
or 2y^2+9y+7=0
or 2y ^2+7y +2y +7=0
or y(2y+7)+1(2y+7)=0
or (y+1)(2y+7)=0
so y=-1,-7/2
if y=-1
then x=7/(-1)=-7
if y=-7/2
then x=14/(-7)=-2
so x=7/y
a/q
x+2y=9
or 7/y+2y=9
or 2y^2+9y+7=0
or 2y ^2+7y +2y +7=0
or y(2y+7)+1(2y+7)=0
or (y+1)(2y+7)=0
so y=-1,-7/2
if y=-1
then x=7/(-1)=-7
if y=-7/2
then x=14/(-7)=-2
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