ini caranya gimna yaa? tolong dibantu

u1 = 7
u2 = 5

b = u2-u1
b = 5-7
b = -2

Suku ke 50?
u50 = a+(n-1)b
u50 = 7+(50-1)-2
u50 = 7 - 98
u50 = -91

Un = U1 + ( n-1 ) x b

U50 = 7 + ( 50-1 ) x -2
U50 = 7 + 49 x -2
U50 = 7 + -98
U50 = - 91 (A)