А) 2m - (2m+6) + (5m-3)

b) x+5y-9x-17y-11x

c) 1.9x-6.7y-3x

1/2 + (3m * (1+3m) + 2m * (1 - 3m)) / (1-9m^2) * (3m-1) ^2 / (2m * (3m+5) = 1/2 + (3m+9m^2+2m-6m^2) / (1-9m^2) * (3m-1) ^2 / 2m (3m+5) = 1/2 + (5m+3m^2) / (1-9m^2) * (3m-1) ^2 / 2m (3m+5) = 1/2 + (m*95+3m) * (3m-1) ^2) / (2m (3m+5) * (1-9m^2) = 1/2 + (3m-1) ^2 / (-2 * (3m-1) (1+3m)) = 1/2 + (3m-1) / (-2 (1+3m)) = (- (1+3m) + 3m-1)) / (-2 (1+3m)) = (-2) / (-2 (1+3m) = 1 / (1+3m)