The first number is this: 4 + x The other number: x So: (4 + x)² + x² = 208 (solve the parentheses squared) 4² + x² + x² = 208 (add like terms and simplify the exponents) 16 + 2x² = 208 (subtract 16 on both sides) 2x² = 192 (divide by two on both sides) x² = 96 (square root both sides) x = √96 √96 = 4√6