Nilai x1+x2 yg memenuhi persamaan 9^x - 12.3^x +27=0 adalah

(3^x)^2-12(3^x)+27=0
3^x1 . 3^x2 = c/a
3^(x1+x2)=27
3^(x1+x2)=3^3
x1+x2=3

9^x - 12.3^x + 27 = 0
3^(2x) - 12.3^x + 27 = 0

Misal 3^x = a
a² - 12a + 27 = 0
(a - 9)(a - 3) = 0

a = 9
3^x = 3²
x = 2

a = 3
3^x = 3
x = 1

Maka...
X1 + X2
= 2 + 1
= 3