If a→,b→,c→,d→ are non - zero coplanar vectors and 2x1a→+2x2b→−c→+3x3d→=0 then
x12+x22+x32≥12
x12+x22+x32≥117
x12+x22+x32≥120
x12+x22+x32≥134
2x1+2x2+3x3=1∴2x1+2x2+3x3≤4+4+9x12+x22+x32⇒x12+x22+x32≥117