Lg^2 x + 2lg 100x -7 =0

Question

Lg^2 x + 2lg 100x -7 =0

Answer 1

Lg² x + 2lg 100x -7 =0

Lg² x + 2(lg 100+lg x) -7 =0

Lg² x + 2( 2+lg x) -7 =0

Lg² x + 4+2lg x -7 =0

Lg² x + 2lg x -3 =0        lg x=a

a²+2a-3=0

D=4+12=16

a=(-2+4)/2=1       lg x=1   x=10

a=(-2-4)/2=-3      lg x= -3  x=1/1000 =0,001