"The square of x..." translates to x²
"...is greater than or equal to 10." translates to ≥ 10.
To determine if 3 is a solution, substitute 3 to the inequality.
[tex]\begin{gathered} x^2\ge10 \\ \text{If }x=3 \\ (3)^2\ge10 \\ 9\ge10 \\ 9\ngeq10 \end{gathered}[/tex]The resulting number, 9 is not greater than 10. Therefore, 3 is not a solution.
