5) [tex] - \sqrt{5} , \sqrt{7} [/tex]
6)
L=3l
A=L*l
[tex]a = 3 {l}^{2} [/tex]
[tex]3 {l}^{2} = 243[/tex]
[tex] {l}^{2} = 81[/tex]
l=9
L=27
7)
[tex]ma = \frac{7 + 63}{2} = 35[/tex]
[tex]mg = \sqrt{7 \times 63} = \sqrt{441} = 21[/tex]
Ma-Mg= 35-21=14
8)
[tex]2 {x}^{2} - 1 = 49[/tex]
[tex]2 {x}^{2} - 50 = 0 \\ {x }^{2} - 25 = 0 \\ (x - 5)(x + 5) = 0[/tex]
x1=5
x2=-5
9)nu stiu
