Here's how we get that:

* Beryllium (Be): This is a group 2 element, meaning it forms +2 ions.

* Dihydrogen phosphate (H₂PO₄⁻): This is a polyatomic ion with a -1 charge.

* Balancing: We need two hydrogen phosphate ions to balance the +2 charge of beryllium.

Therefore, the formula is Be(H₂PO₄)₂.