Question

if 3x+2y=12 and xy=6,find the value of 9xsquare+4y

Answer 1

Heya user this is your answer..

on squaring both sides we get,
(3x+2y)² = 12²
using (a+b)² = a²+b²+2ab identity we get..

3x²+2y²+2*3x*2y = 12²
9x²+4y²+12xy = 144

xy=6 given so by putting 6 in the place of xy we get..

9x²+4y²+12*6=144
9x²+4y²+72=144
9x²+4y²=144 - 72
9x²+4y² = 72 is the correct answer..

Hope it helps..

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