need help pls Evaluate the sum sigma6i 3 2i 5 The nth term

need help pls

Evaluate the sum. sigma^6_i = 3 (2i - 5) The nth term of a sequence is given. Find the first 4 terms. a_n = 3n - 7

Solution

8)

i= 3 to 6

( 2*3 - 5 ) + ( 2*4 - 5 ) + ( 2*5 - 5 ) + ( 2*6 - 5 )

= 1 + 3 + 5 + 7

= 16 (answer)

9)

an = 3n – 7
a1 = 3*1-7 = -4

a2 = 3*2 – 7 = -1

a3 = 3*3 - 7 = 2

a4 = 3*4 – 7 = 5 answer : -4 , -1, 2, 5