1) 7^x * 49 + 4*7^x = 347
7^x*(49 =4/7) = 347
7^x *(347/7) = 347
7^x = 7
x = 1
2) 3^(2x) - 24*3^x - 81 = 0
D = (24)^2 + 4*81 = 900
3^x = (24 - 30)/2
3^x = - 3 (3^x > 0)
3^x = (24 + 30)/2
3^x = 27
3^x = 3^3
x = 3
3) 2*(2^2x) - 5*(2^x)*(3^x) + 3*(3^2x) = 0 / (3^2x)
2*(2/3)^(2x) - 5*(2/3)^x + 1 = 0
D = 25 - 4*2*1 = 16
(2/3)^x = (5 - 4) /4
(2/3)^x = 1/4
x1 = log(2/3) (1/4)
(2/3)^x = (5 + 4) /4
(2/3)^x = 9/4
(2/3)^x = (2/3)^2
x2 = 2