Răspuns:
[tex]\large\bf\red{\underline{mg = 7}}[/tex]
Explicație pas cu pas:
[tex]\bf{a = 9 - 4 \sqrt{2} }[/tex]
[tex]\bf{b = 9 + 4 \sqrt{2} }[/tex]
[tex]\large\bf\purple{\underline{mg = \sqrt{a \times b} }}[/tex]
[tex]\bf{ = > mg = \sqrt{81 - 16 \times 2} = \sqrt{81 - 32} = \sqrt{49} = \sqrt{7 {}^{2} } = }[/tex]
[tex]\large\bf\red{\underline{7}}[/tex]