Question

http://postimg.org/image/sbn00ra07/

@amistre64

Answer 1

I just don't know what to do with that n exponent

Answer 2

oh and also as a side note
we haven't learned about logarithms yet

Answer 3

all that (-1)^n does is alternate the sign;

7/9 = (-1)^n n/(n+4)

7(n+4) = (-1)^n 9n

this can be thought of as:

7(n+4) = -9n or 7(n+4) = 9n

and then test out the solutions afterwards

Answer 4

if n is even, (-1)^n = 1

if n is odd, (-1)^n = -1

Answer 5

Oh Okay so (I know this will sound stupid but) but to me it looked like the (-1)^n just disappeared lol

um I didn't get what you meant by saying that "(-1)^n does is alternate the sign"

Answer 6

what is:

(-1)^1 ?
(-1)^2 ?
(-1)^3 ?
(-1)^4 ?

for each n value, what are we multiplying: 9n, by?

Answer 7

1?

Answer 8

you have to work out the powers of -1 that i posted, do them all and tell me what you get.

Answer 9

um

(-1)^1= -1

(-1)^2 = 1

(-1)^3 = -1

(-1)^4 =1

Answer 10

(-1)^n doesnt disappear, its just affecting the problem is a rather simple but profound manner.

see how for each value of n, the sign of 1 alternates back and forth

Answer 11

yes

Answer 12

it's because as you said

"if n is even, (-1)^n = 1

if n is odd, (-1)^n = -1
"

Answer 13

(-1)^1 9(1) = -9(1)

(-1)^2 9(2) = 9(2)

(-1)^3 9(3) = -9(3)

etc ... so our solution approach is going to either have

7(n+4) = 9n or 7(n+4) = -9n

work both solutions and then we have something to test out.

Answer 14

Ohhh!!! Okay! I see meaning the exponent can either result it as -1 or 1 depending if the power is even or odd and then plug it back into the equation?

Answer 15

yep, so lets just conclude that it can be -1 or 1 and test both outcomes

Answer 16

if it's 7(n+4) = 9n then my value for n is gonna be 14

and for 7(n+4) = -9n it's gonna be = 1.6875

Answer 17

they said the answer is suppose to be 14 though

Answer 18

2n = 28 ; n=14 is a valid solution

16n = -28 ; well, n i believe has to be a nonnegative integer, (whole number?) so this ones out

test n=14, what do we get?

Answer 19

oh wait sorry there was mistake in my answer

Answer 20

it's suppose to be -1.6875

Answer 21

our process gives us to possible solutions, its up to use to determine which one is valid.

since n= 0,1,2,3,4,5,.... our solution as to be an integer that is not negative.

n=14 or n=-7/4

yeah, n=14 is the only valid result

test it out and see if it works

Answer 22

(-1)^14 * (14/14+4) = 7/9

yes it works!

Answer 23

:) yay!!

Answer 24

thank you so much sir!!!

Answer 25

youre welcome

Answer 26

:D