Question

计算(1)y分之5x乘15x平方分之y (2)x分之2a平方b除以(-2ab) (3)x-1分之1+1+x分之1 (4)ab分之c-bc分之a (5)a

(5)a平方-1分之a+a平方-1分之3a+1+1-a平方分之2a+3

Answer 1

5x/y × y/(15x²) = 1/(3x)

2a²b/x ÷ (-2ab) = -a/x

1/(x-1) + 1/(1+x) = [(x+1)+(x-1)]/[(x-1)(x+1)] = 2x/(x²-1)

c/(ab) - a/(bc) = (c²-a²)/(abc)

a/(a²-1) + (3a+1)/行简李(a²-1) + (2a+3)/(1-a²)
= a/(a²咐拿-1) + (3a+1)/(a²-1) - (2a+3)/(a²-1)
= [a + (3a+1) - (2a+3)]/(a²-1)
= (2a-2/(a²-1)
= 2/档迟(a+1)