Question

Diketahui :
U5 = 14
U8 + U11 = 55

ditanyakan :
U20 = ?

Answer 1

U5 = a+4b = 14
U8+U11 = a+7b + a+10b = 55
2a+17b= 55

a+ 4b = 14 |×2|
2a+17b=55 |×1|
=> 2a+8b = 28
=> 2a+17b = 55
----------------------- -
-9b = -27
b =3
a + 4b = 14
a +4(3) = 14
a+12= 14
a = 2
U20 = 2+(20-1) 3
= 2+(19)3
= 2+(57)
= 59
diteliti lagi yab

Answer 2

U5 = a+4b ........(1

U8 + U11 = 55
(a+7b) + (a+10b) = 55
2a + 17b = 55 ..........(2

substitusi (1 dan (2
a + 4b = 14 | x2
2a + 17b = 55 | x1

2a + 8b = 28
2a + 17b = 55 (abis tuh dikurang)

-9b = -27
b = 3

masukan
a + 4b = 14
a + 4(3) = 14
a + 12 = 14
a = 2