Nomer 5 gimana ya caranya sama jawabannya

eliminasi
4^x+1 + 2^y = 20
2^x-1 - 2^y = -3
----------------------- +
4^x+1 + 2^x-1 = 17
4^x.4 + 2^x.2^-1 = 17
4.4^x + (½).2^x = 17 kalikan 2
8.4^x + 2^x = 34
8.(2^x)² + 2^x - 34 = 0
misalkan 2^x = p
8p² + p - 34 = 0
(8p + 17)(p - 2) = 0
p = -17/8 (tidak memenuhi)
p = 2
2^x = 2
2^x = 2¹
x = 1
2^(1-1) - 2^y = -3
2^0 - 2^y = -3
1 - 2^y = -3
1 + 3 = 2^y
4 = 2^y
2² = 2^y
y = 2
jadi x = 1 dan y = 2
^ tanda pangkat