2.次の式を展開せよ。 (1)(bat8b) 120-7b) =100²-19ab-566- (2) (2x²y)² 4x² - 4x³y² + y + (3) (3 at b-20) ² =(A-2C)² ² = A* - 2 AC + 4c² = ( ³a+b) ² - 2 (3atb/c + 4c² =9a²+ babth- bca-bc +4c² =9a²+ b²+4 ₁² + bab-2bc-bca (4)(2²-2x-1)(x-2x-2) = (A-1) (A-2) + - = (x²= 2X) = 3 (x²-2x) + + =x²-4x+4x-3x+bx+2 =x²-4₂³ + x² + b 2 + 2 t -5) (a−b) (a+b) (a² + b² ) = (a²-b²₂) (a²+ b² ) a²-64