Question

If 1+2+3+...+r=n^2, where n is an integer less than 100, the possible values of r is/are?

Answer 1

use the formula 1+2+3+...+r = r*(r+1)/2

Answer 2

seems odd how they give you 2 variables, you sure it's not

1+2+3+...+n=n^2

Answer 3

the options are 1, 8, or 49

Answer 4

so see what you get when you compute 1+2+3+...+8 and also 1+2+3+...+49

Answer 5

when r = 1, you have the trivial sum of just 1 (you don't have any other addends)

Answer 6

336 and 2401

Answer 7

yep

Answer 8

how are you getting 336?

Answer 9

and 2401

Answer 10

sorry 36 lol (1+...+8)
and 1225 is (1+...+49)
sorry lol

Answer 11

so the sum from 1 to 8 gives you a number that's a perfect square

n^2 = 36 which means n = 6

Answer 12

yep

Answer 13

35^2=1225

Answer 14

and summing from 1 to 49 gives n^2 = 1225 which means n = 35, yes

Answer 15

yes so its 8 and 49

Answer 16

so 1, 8, 49 look good

Answer 17

could you help me with a few more?

Answer 18

sure

Answer 19

ill post it