If 3x+5y = 11 and xy = 2, find the value of 9x2+25y2
Given that,
3x + 5y = 11
Squaring both sides, we get
(3x + 5y)2 = (11)2
(3x)2 + (5y)2 + 2 (3x) (5y) = 121
9x2 + 25y2 + 30xy = 121
9x2 + 25y2 + 30 (2) = 121
9x2 + 25y2 = 121 – 60
9x2 + 25y2 = 61