Jumlah akar-akar persamaan [tex]5^{x+1} + 5^{1 - x} = 11 [/tex] adalah ......................

EksPonenSiaL

Misal :
5^x = a

5^(x + 1) + 5^(1 - x) = 11
5a + 5/a = 11 ... ( × a)
5a² - 11a + 5 = 0
a1 . a2 = c/a = 5/5 = 1
5^x1 . 5^x2 = 1
5^(x1 + x2) = 5^0
x1 + x2 = 0