Apply constraint to equation, Wolfram Alpha.

Question

I think it's being able to handle gracefully this one:

a * -2 + b * 5 = -9

Yields me several interpretations, one of them I like:

a = 5n + 2, b = 2n - 1, n ∊ ℤ

Now because a and b are Stack Exchange downvotes and upvotes on questions; and if I fed a 0 to the solution it handed me, it would yield a = 2, b = -1 where b fails to be in ℕ; I tried to apply an additional constraint to it:

a * -2 + b * 5 = -9 such that a > -1 and b > -1

But I'm unable to find such interpretation in the answers it's proposing me.

How to / What am I doing wrong?

Answer 1

I think

a * -2 + b * 5 = -9, a > -1, b > -1

did what I wanted. At first I thought it was interpreting a tuple, but I finally found

a = 5n + 2, b = 2n - 1, n ∊ ℤ, n ≥ 1

as the last interpretation.