Răspuns:
[tex]3. \: x = {( \sqrt{2} + \sqrt{3} ) }^{2} + (1 - \sqrt{6} )(1 + \sqrt{6} ) \\ x = ( \sqrt{4} + 2 \sqrt{6} + \sqrt{9} ) + ( { \sqrt{1} }^{2} - { \sqrt{6} }^{2} ) \\ x = 2 + 2 \sqrt{6} + 3 + 1 - 6 \\ x = 2 \sqrt{6 } = 4.89 \\ x = 4.89 < 5[/tex]
[tex]5.n = 8 {( \sqrt{3} - \sqrt{7}) }^{2} - (6 + 4 \sqrt{3} )(4 \sqrt{3} - 6) + 4 {(2 \sqrt{3} + \sqrt{7} )}^{2} \\ n = 8(3 - 2 \sqrt{21} + 7) - (48 - 36) + 4(12 + 7) \\ n = 24 - 16 \sqrt{21} + 56 - 12 + 76 \\ n = 144 - 16 \sqrt{21} \\ n = {12}^{2} - {4}^{2} \times {21}^{2 } = patrat \: perfect[/tex]
[tex]6.e(x) = {(3x - 1)}^{2} - (2x - 1)(5x - 2) + 3x - 7 \\ e(x) = {9x}^{2 } -6x + 1 - ({10x}^{2} - 4x - 5x + 2) + 3x - 7 \\ e(x) = 9 {x}^{2} - 6x + 1 - 10 {x}^{2} + 4x + 5x - 2 + 3x - 7 \\ e(x) = - {x}^{2} + 6x - 8 [/tex]
