Сократить выражение b / (a-1) ^2-ba^2 / (1-a) ^2

B / (a-1) ^2-a^2b / (- (a-1)) ^2 = (- (a-1)) ^2*b-a^2b * (a-1) ^2 / (- (a-1)) ^2 * (a-1) ^2 = (a-1) ^2*b-a^2b * (a^2-2a+1) / (a-1) ^2 * (a-1) ^2 = (a^2-2a+1) b-a^4b+2a^3b-a^2b / (a-1) ^4=a^2b-2ab+b-a^4b+2a^3b-a^2b / (a-1) ^4=-2ab+b-a^4b+2a^3b / (a-1) ^4