[tex] {3k}^{2} = 243 \\ = > {3k}^{2} - 243 = 0 \\ = > 3( {k}^{2} - 81) = 0 \\ = > 3[(k) ^{2} - {(9)}^{2} ] = 0 \\ = > 3(k - 9)(k + 9) = 0 \\ = > (k - 9)(k + 9) = 0 \\ = > k = 9 \: \: or \: \: - 9[/tex]
Hope you could get an idea from here.
Doubt clarification - use comment section.
