c,

=>3x(3^2+1)=810

=>3x.10=810

=>3x=81=34

=>x=4

Vậy x=4

a)(6x - 39) : 3) * 28 =44956
=>(2x - 13 ) * 28  = 44956
=> 2x - 13 = 11239/7
=> 2x = 11330/7
=> x = 5665/7
b)3^7 * 3^3 -7x =2^3*3^2
=> 3^10 - 7x = 8 * 9
=> 59049 - 7x = 72
=> -7x =  - 58 977
=> x = 58977/7
c)3^x + 3^x+2 +810
= 2 * 3^x + 810