Question

Jika 4^x+4^-x = 7
8^x+8^-x=??
makasih banyakk

Answer 1

4^x + 4^-x = 7
(2^x + 2^-x)^2 - 2 = 7
2^x + 2^-x = 9

(4^x + 4^-x)(2^x + 2^-x) = 7(9)
(2^2x + 2^-2x)(2^x + 2^-x) = 63
2^3x + 2^-3x + 2^x + 2^-x = 63
8^x + 8^-x + 9 = 63
8^x + 8^-x = 63 - 9 = 54