Question

Write an equation whose solution is not a whole number

Answer 1

Answer:

2x + 5y = 90

x and y are whole numbers. how many (x,y) can this equation get?

I thought it like this;

2x = 90-5y

x = (90-5y)/2

x is a whole number so must be divisible by 2. So I thought--- by giving y the values {0, 2, 4, 6, 8, 10, 12, 14, 16} it can be divided by 2.

There can be 9 (x,y)s

If it is true, is there a better way to do it? And If not where did I make the mistake?

Thanks!