[tex]\implies {\blue {\boxed {\boxed {\purple {\sf { \: ({ \: z - 2 \: })^{2} \: }}}}}}[/tex]
[tex]\large\mathfrak{{\pmb{\underline{\orange{Step-by-step\:explanation}}{\orange{:}}}}}[/tex]
[tex] {z}^{2} - 4z + 4[/tex]
[tex] = {z}^{2} - 2z - 2z + 4[/tex]
Taking "[tex]z[/tex]" as common from first two terms and "[tex]2[/tex]" from last two terms, we have
[tex] = z \: ( \: z - 2 \: ) - 2 \: ( \: z - 2 \: )[/tex]
Taking the factor [tex](z-2)[/tex] as common,
[tex] = ( \: z - 2 \: )( \: z - 2 \: )[/tex]
[tex] = {( \: z - 2 \: )}^{1 + 1} [/tex]
[tex] = ({ \: z - 2 \: })^{2} [/tex]
[tex]\red{\large\qquad \qquad \underline{ \pmb{{ \mathbb{ \maltese \: \: Mystique35❦}}}}}[/tex]