MATHEMATICS · Subjective · AoPS · Mathematics · Multi-Variable Linear Equations · Multi-Variable Linear Equations
Problem
Determine x2+y2+z2+w2, if 22−12x2+22−32y2+22−52z2+22−72w2=1, 42−12x2+42−32y2+42−52z2+42−72w2=1, 62−12x2+62−32y2+62−52z2+62−72w2=1, and 82−12x2+82−32y2+82−52z2+82−72w2=1.