Find the value of 4x^2+9y^2 if 2x+3y=18 and xy= 5
Answers
Answered by
103
2x + 3y = 18
take square both sides ,
(2x +3y)² = 18²
4x² + 9y² + 2.2x.3y = 324
(4x² + 9y²) + 12xy = 324
[ given , xy = 5 put it ]
(4x² + 9y²) + 12×5 = 324
(4x² + 9y²) = 324 -60 = 264
hence,
4x² + 9y² = 264
take square both sides ,
(2x +3y)² = 18²
4x² + 9y² + 2.2x.3y = 324
(4x² + 9y²) + 12xy = 324
[ given , xy = 5 put it ]
(4x² + 9y²) + 12×5 = 324
(4x² + 9y²) = 324 -60 = 264
hence,
4x² + 9y² = 264
pankaj12je:
nah
then
actually in last line there was a typo error 164 instead of 264 :)
refresh plz then see
kk :)
refresh plz then see
Na na 264 is right ans thank u
kk bro now its 264 awsm answering :-)
:-)
M girl
Answered by
38
Hey there !!!
2x+3y=18-------------Equation 1
squaring Equation 1
(2x+3y)²=18²
4x²+2*2x*3y+9y²=18²
4x²+9y²+12xy=324
But given that xy=5
So,
4x²+9y² =324- 12*5
4x²+9y²= 324-60 = 264
Hope this helped you..................
2x+3y=18-------------Equation 1
squaring Equation 1
(2x+3y)²=18²
4x²+2*2x*3y+9y²=18²
4x²+9y²+12xy=324
But given that xy=5
So,
4x²+9y² =324- 12*5
4x²+9y²= 324-60 = 264
Hope this helped you..................
Thank u so much
Similar questions