Tìm x biết: (4/9)^x = (16/81)^12; (25/9)^2x + 1 = ( 27/125)^15

Tìm x biết:
a) (4/9)^x = (16/81)^12
b) (25/9)^2x + 1 = ( 27/125)^15
c) (3/2)^-x + 3 = ( 16/81)^21
d) 2.3^x+2 + 4.3^x+1 = 10.3^6
e) 5.2^x + 3.2^x + 2 = 5.2^5 + 3.2^7
g) (1/2 - 1/3 ) 6^x + 6^x+2 = 6^10 + 6^7
h) ( 1/2 - 1/6). 3^x+4 - 4.3^x= 3^16 - 4.3^13