Given expression:
[tex]=\text{ 7x(x + 4)}[/tex]Expanding:
[tex]\begin{gathered} =\text{ 7x }\times\text{ x + 7x }\times\text{ 4} \\ =\text{ 7 }\times\text{ x }\times\text{ x + 7 }\times\text{ x }\times\text{ 4} \\ =\text{ 7 }\times x^2\text{ + 7 }\times\text{ 4 }\times\text{ x} \end{gathered}[/tex]Simplifying the expression:
[tex]\begin{gathered} =7\times x^2\text{ + }28\times x \\ =7x^2\text{ + 28x} \end{gathered}[/tex]Answer:
[tex]7x^2\text{ + 28x}[/tex]