mycroft holmes
Last Activity: 14 Years ago
Equivalently we have to prove that 2x2+4xy+6y2-12x-4y+22>=0
From Cauchy Schwarz (CS) Inequality, 4 [(x+2y)2+(y-1)2+(y-1)2+(x-6)2] >= (x+2y+1-y+1-y+6-x)2 = 64
Hence, (x+2y)2+(y-1)2+(y-1)2+(x-6)2 >= 16
or 2x2+4xy+6y2-12x-4y+22>=0
Since the CS equality condition cannot be met here, we have 2x2+4xy+6y2-12x-4y+22>0