Q12 of 116 Page 6

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


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