Verified answer

Hi,

1) a1=3,an=98,n=20

98 = 3 + d(20 - 1)

98 = 3 + 19d

95 = 19d

5 = d

a(n) = 3 + 5(n - 1) <==ANSWER

2) 29+34+39+44...n=9

a(n) = 29 + 5(n - 1)

S(9) = 9/2(2*29 + 5(9 - 1))

S(9) = 9/2(2*29 + 5(8))

S(9) = 9/2(58 + 40)

S(9) = 9/2(98)

S(9) = 441 <==ANSWER

3) a1= -10, d= -8, n=7

a(n) = -10 - 8(7 - 1)

a(n) = -10 - 8(6)

a(n) = -10 - 48

a(n) = -58 <==ANSWER

This is stigma notation

4) 5

∑ (9k-12) = (9(1)-12) + (9(2)-12) + (9(3)-12) + (9(4)-12) + (9(5)-12) = -3 + 6 + 15 + 24 + 33 = 75

k=1

5) 13

∑ (10k-8) =

k=5

(10(5)-8) + (10(6)-8) + (10(7)-8) + (10(8)-8) + (10(9)-8) + (10(10)-8) + (10(11)-8) + (10(12)-8) + (10(13)-8) = 42 + 52 + 62 + 72 + 82 + 92 + 102 + 112 + 122 = 738

I hope that helps!! :-)

Evaluate Each Arithmetic Series Described

Evaluate The Series