(у-3)²+3(у+2)(у-2)=9+4у²
у²-6у+9+3(у²-4)=9+4у²
у²-6у+9+3у²-12=9+4у²
4у²-4у²-6у=9-9+12
-6у=12
у=-2
(у-3)² + 3(у+2)(у-2) = 9+4у²,
у²-6у+9 + 3у²-12 = 9+4у²,
у²-6у+9 + 3у²-12 - 9-4у² = 0,
-6у - 12 = 0,
6у = -12,
у = -2
