Question

Please Help!!

Find an explicit rule for the nth term of the sequence.

-3, -15, -75, -375, ...

an = 5 • -3n + 1

an = -3 • 5n - 1

an = 5 • -3n

an = -3 • 5n

Answer 1

a_n = 5 • -3^n + 1

a_n = -3 • 5^n - 1

a_n = 5 • -3^n

a_n = -3 • 5^n

Answer 2

test one by one to see which is the correct answer
let test the first one \(a_n= 5*(-3)^{n+1}\) , is it correct form of the option?

Answer 3

yes

Answer 4

now let n =2, so a2 = 5* (-3)^3 = 5*(-27) = -135 while your second number is -15. So, the first option is not the correct one.
how about the second option?? you test

Answer 5

n=2 so a2=-3(5) =-15

Answer 6

n=3 so a3= -3(5^2) =-75

Answer 7

yup, however, to make sure of it, test for n =3

Answer 8

so is the second choice the answer?

Answer 9

oh, you got it. Good!! the last one, please

Answer 10

should test all of the term to get 100% correct. hihihi

Answer 11

a4= -3(5^3)= -375

Answer 12

yay! thank you

Answer 13

BiG BINGO