What is the largest number for which x2 + x4 < 10

The largest number for which x2 + x4 < 10 is 5. Option A (4) and C (6) both result in an equal or greater value than 10 when substituted into the equation. Option D (7) results in a value greater than 10 when squared and then added to itself raised to the fourth power. Option B (5) is the only number that when squared and then added to itself raised to the fourth power results in a value less than 10. Therefore, 5 is the largest number that fulfills the equation x2 + x4 < 10.