А)15/x=5/8 б)24/x=8/7 в)12/x=4/5 г25/x=5/7

а)15/x=5/8

5x = 15·8

x = 3·8

x = 24

б)24/x=8/7

8x = 24·7

х = 3·7

х = 21

в)12/x=4/5

4х = 12·5

х = 3·5

х = 15

г)25/x=5/7

5х = 25·7

х = 5·7

х = 35

f"(х)=1/2(3х+2)^(-1/2)*3+4x^3=3/2(корень(3х+2))+4x^3

a³-25a=a(a²-25)=a(a-5)(a+5)