X2 - 10x + _ "find value that completes the square and rewrite as perfect square" what does it mean by "rewrite as perfect square"

How to do this , and can some one explain

Carlos spent 1 1/4 hours doing his math homework he spent 1/4 of his time practicing his multiplication facts how many hours to carlos been practicing his multiplication facts

Venita is sewing new curtains. the table below shows the relationship between the number of stitches in a row and the length ofthe row.sewingnumber of stitches length (cm)51 131532024306what is the relationship between the number of stitches and the length? othe number of stitches istimes the length.o. the number of stitches is 3 times the length.