Question

What is the 5th term of this sequence?
a1= -3, an= -2a n-1

Answer 1

32

Explanation:

an = a1 + (n - 1)d

a5 = 32=a1 + 4d

a10=57 = a1 + 9d

57=a + 9d

32=a + 4d

25=5d

A) d=5

32=a1 + 4*5

B) a1=12

57=a1 + 9*5

57=a1+45

B) 12=a1

an = a1 + (n - 1)d

an = 12 + 5(n - 1)

an = 12 + 5n - 5

C) an = 5n +7

D) a22 = 5*22 +7=117

Answer 2

Answer:start with an=a1+(n-1)d

a5=a1+4d=22

a15=a1+14d=62

Therefore, subtracting

-10d=-40

d=4

a5=22=a1+16

a1=6

6,10,14,18,22,a10 is 42, a15 is 62.

an=6+(n-1)*4

Explanation: