diketahui a + b = 3 dan a*2 + b*2 = 5 tentukan nilai dari a*4 + b*4

a+b = 3
a²+b² = 5

a²+b² = 5
(a+b)(a-b) = 5
3(a-b) = 5
3a-3b = 5


a+b = 3 (x3)
3a-3b = 5 (x1)
-------------------
3a+3b = 9
3a-3b = 5
-------------------(dikurang)
6b = 4
b = 4/6
b = 2/3

a+b = 3
a = 3-2/3
a = 9/3-2/3
a = 7/3

a^4+b^4 = ...
(7/3)^4+(2/3)^4 = ...
2401/81 + 16/81 = 2417/81 atau 29,84

Maaf jika ad kesalahan :)