Question

if 9x2 + 16y2 = 60 and 3x + 4y = 6, then the value of xy is

Answer 1

9x^2 + 16y^2=60
3x + 4y = 6
(3x + 4y)^2= 6^2
9x^2 + 16y^2+24xy=36........eq1
substituting the value of 9x^2 + 16y^2 in eq1
60+24xy=36
24xy=36-60
24xy=-24
xy=-1

hope this helps!!