How many solutions are in the solution set for the equation 3x^2=21

To solve the equation \( 3x^2 = 21 \), we can start by dividing both sides by 3:

\[ x^2 = \frac{21}{3} \]

This simplifies to:

\[ x^2 = 7 \]

Next, we take the square root of both sides:

\[ x = \pm \sqrt{7} \]

This gives us two solutions: \( x = \sqrt{7} \) and \( x = -\sqrt{7} \).

Therefore, the number of solutions in the solution set is two.