Question

решите уравнение

 

$x^{frac{20}{21}}+x^{frac{5}{42}}=12x^{-frac{5}{7}}$

Answer 1

x^40/42  +  x^5/42=12x^-30/42

x^5/42(x^35/42+1)=12x^-30/42

x^35/42+1=12x^-35/42

x^5/6+1=12x^-5/6

x^5/6=t, t>0

t+1=12/t

t^2+t-12=0

t1=-4<0

t2=3

x^5/6=3

x=3^6/5    =3*3^1/5