Answer:
[tex]\ast=16a^2[/tex]
Step-by-step explanation:
Use formula for a square of a sum:
[tex](x+y)^2=x^2+2xy+y^2.[/tex]
Note that
- [tex]49=7^2;[/tex]
- [tex]56a=2\cdot 28a=2\cdot 7\cdot 4a.[/tex]
Then instead of * should be the square of the term 4a that is [tex](4a)^2=16a^2.[/tex]
Then
[tex]16a^2+56a+49=(4a+7)^2.[/tex]
