∛3 =3¹/³
∛х / х³ = х¹/³ ⁻ ³ = х ⁻² ²/³ = 1/х² ²/³ = 1 / (х²* ∛х²)
13z²+52z-(z+4)=0
13z²+52z-z-4=0
13z²+51z-4=0
D=2601+208= 2809
z1= (-51-53)/26= -4
z2= (-51+53)/26= 1/13