a)24a⁴/ b³ * b⁴/8a⁴=3в
б)7xy²/ 2 : 14x²y²=1/4y
в)m+2n/m-n * m²-n²/5m+10n=m+2n/m-n * (m-n)(m+n)/5(m+2n)=(m+n)/5
г)x²-2x+1/x²-25 : x-1/x²+5x= (х-1) ^2/(x-5)(x+5) : х-1/х(х+5)=
=x^2-x/x-5
