5) 4/х+5=1/х^2

4/х+5-1/х^2=0

( 4х+5х^2-1)/х^2 =0|*х^2

4х+5х^2-1=0

5х^2+4х-1=0

D=16+20=36

x1= -4+6/10=1/5

x2=-4-6/10=-1

Ответ :-1; 1/5