Question

log12 (根号x+四次根号x)=1/2log9 x解方程,

Answer 1

设 x^(1/4)=t,则 x=t^4, √x = t²

lg(t²+t) / lg12 = 4lgt / 2lg9

[lgt + lg(t+1)] / [lg3 + lg4] = lgt / lg3

lg(t+1) / lg4 = lgt / lg3

lg(t+1) / lgt = lg4 / lg3

1+1/t=4/3

t=3

x=3^4=81