The difference between the solution to the equation x² = a is 30.
x² = a
x = √a or x = -√a.
The difference between the solutions satisfies the condition
√a - (-√a) = 30
2√a = 30
√a = 15
a = 15² = 225
Check the answer.
When x = +√a,
x² = (√a)² = a Correct
When x = -√a,
x² = (-√a)² = a Correct
Answer: a = 225, and the answer checks out to be correct.