tolong bantu kak pleaasee no 3.4dan 5

3. dik: a = 15
R = 5
dit: u30 dan s30?
jwb: u30 = 15 + (30-1)5
= 15 + 145
= 160

s30 = 1/2(30)(2(15)+(30-1)5)
= (15)(175)
= 2625

4. dik: s5 = -93
R = 2
dit: a dan u3?
jwb: -93 = a(2^5 - 1)/2-1
-93 = a(31)
-3 = a

u3 = -3.2^3-1
= -3.2^2
= -3.4
= -12

5. dik: a = 6
u2 = 2
dit: S~?
jwb: r = u2/a
= 2/6
= 1/3

S~ = 6/1-1/3
= 6/2/3
= 18/2
= 9