Question

Help! I'll give a medal!!

Input Output
1 3
2 -1
3 -5
4 -9
5 ?
...n ?

I have to complete the table...I can't figure out the pattern though, any suggestions?

Answer 1

+2-2

Answer 2

look at the outputs they are an arithmetical sequence with common difference -4

Answer 3

i think its -4 idk

Answer 4

Ok the first blank would be -13 @cwrw238 ? right

Answer 5

the terms in an AP are a, a+d, a+ 2d + .. = a+(n-1)d

Answer 6

yes

Answer 7

and nth term is a+ (n-1)d

here a is the first term = 3 and d = -4

Answer 8

ok, but I have to find what equation or pattern they use to get from the input to the output

Answer 9

the nth term gives the pattern
plug in a=3 and d = -4

Answer 10

a + (n - 1)d
3 + (n -1)-4
Is that how it should look?

But I don't need to find n....

Answer 11

right - no just the nth term

you can simplify that if you like

nth term = 3 + (n-1)*-4

= 3 - 4n + 4
= 7 - 4n

Answer 12

we can check if this is correct

try 5th term;

= 7 - 4(5) = 7 - 20 = -13

Answer 13

6th term = 7 - 4(6) = -17 which is correct

Answer 14

ohhhh I see....ok so the formula I use is 7 - 4n....so then the blank next to the nth input would b the formula 7-4n becuz I use that to find any output...right?

Answer 15

yes

Answer 16

awesome! thank you very much!!

Answer 17

yw