Step: Putting the value of m and n in required equation m=9x2ā4xy+5y2
and n=ā3x2+2xyāy2
Then, 2n=2[ā3x2+2xyāy2]
=ā6x2+4xyā2y2
ām+2n=9x2ā4xy+5y2+(ā6x2+4xyā2y2)
=9x2ā6x2ā4xy+4xy+5y2ā2y2
=3x2+3y2
Hence, the answer is 3x2+3y2.