Question

3x^2-21=0

Answer 1

\[3x^2-21=0\]\[3x^2=21\]\[x^2=\frac{21}{3}=7\]\[\color{red}{x=7}\]

Answer 2

Sorry\[\color{blue}{x=\sqrt{7}}\]

Answer 3

\[x = \pm \sqrt(7)\]
To be specific

Answer 4

\[x=\pm2.65\]approximately;)