Question

if 2 X + 3 Y is equal to 8 and X Y is equal to 4 then find the value of 4 x square + 9 y square

Answer 1

2x+3y = 8

=> ( 2x+3y )2 = (8)2  { On squaring both the sides }

=> (2x)2 + (3y)2 +2 (2x) (3y) = 64       { Using, (a+b)2 = a2 +b2 +2ab }

=> 4x2 + 9x2 +12 xy = 64

=> 4x2 + 9x2 + 48  = 64  { On Putting the value of xy }

=> 4x2 + 9x2 = 64-48

=> 4x2 + 9x2 = 16.

HOPE THIS   HELPED !!

Answer 2

2x+3y=8

square on both sides,

(2x+3y)^2 =8^2

4x^2 + 9y^2 +2(2x*3y)=64

4x^2 + 9y^2 + 12xy= 64

4x^2 + 9y^2 +(12*4) = 64

4x^2 +9y^2 = 64-48

4x^2 + 9y^2 = 16