Answer:
[tex]\large\boxed{2\sqrt7}[/tex]
Step-by-step explanation:
[tex]\text{The geometric mean:}\ \sqrt[n]{a_1\cdot a_2\cdot ...\cdot a_n}\\\\\text{For two numbers}\ a\ \text{and}\ b:\ \sqrt{ab}\\\\\text{We have 4 and 7. Substitute:}\\\\\sqrt{4\cdot7}\qquad\text{use}\ \sqrt{ab}=\sqrt{a}\cdot\sqrt{b}\\\\=\sqrt4\cdot\sqrt7=2\sqrt7[/tex]
