I need help arranging cards in a 4 x 4 grid with numbers 1-9 so that the sum of each row and each column is 20. This what the grid looks like:

8, 2, 8, 2

7, 3, 7, 3

6, 4 6, 4

9, 1, 9, 1

Step-by-step explanation:

In the picture, it shows two of each number so I'm gonna base it off the picture but let me know if I should base it off the wording.

So we know that half of 20 is 10. This will be valuable information. So we need the sum of two numbers to equal 10. So for the rows we can just do 8+2+8+2, 7+3+7+3, 6+4+6+4, 9+1+9+1.

Since there are 18 numbers, I'm assuming we don't have to use all of them.

9, 1, 9, 1

2, 8, 2, 8

3, 7, 3, 7

6, 4, 6, 4

Step-by-step explanation:

you would have to have the numbers repeat so it works, for instance, you could do 9,1,9,1 as the first row then 2,8,2,8 as the second row and for the third row you could do 3,7,3,7 and for the fourth row you could do 6,4,6,4 so both the columns and rows add to 20

hello from mrbilldoesmath!

answer:

x - 3

discussion:

x^2 - 9 = (x-3) (x+3)   so

(x^2-9)/ (x + 3) = x-3

you,

mrb