cara persamaan eksponesial

2^x = a
2^y = b

4^(x + 1) + 2^y = 20
4 . 4^x + 2^y = 20
4 (2^x)² + 2^y = 20
4a² + b = 20 ... (1)

2^(x - 1) - 2^y = -3
1/2 . 2^x - 2^y = -3
1/2 a - b = -3 ... (2)

(1) + (2) = 20 + (-3)
4a² + 1/2 a = 17 ... ( × 2)
8a² + a = 34
8a² + a - 34 = 0
(8a + 17)(a - 2) = 0
a = -17/8 tdk memenuhi
a = 2
2^x = 2
x = 1

4a² + b = 20
b = 20 - 16
b = 4
2^y = 4
y = 2

▶
x + y = 1 + 2 = 3

semoga membantu yaa :)