Răspuns:
[tex]7) \\ a) \\ (x {}^{2} - 5 {}^{2}) \times( x {}^{2} - 5 {}^{2} )[/tex]
[tex](x {}^{2} - 25) \times( x {}^{2} - 25)[/tex]
[tex]x {}^{4} - 25x {}^{2} - 25x {}^{2} + 625 [/tex]
[tex]x {}^{4} - 50x {}^{2} + 625[/tex]
[tex]b)[/tex]
[tex](x {}^{2} - 16)(x {}^{2} - 16 )[/tex]
[tex]x {}^{4} - 16x {}^{2} - 16x {}^{2} + 256[/tex]
[tex]x {}^{4} - 32x {}^{2} + 256[/tex]
[tex]c)[/tex]
[tex](2x {}^{2} - 1)(2x {}^{2} - 1)[/tex]
[tex]4x {}^{4} - 4x {}^{2} + 1[/tex]
[tex]d)[/tex]
[tex](3x {}^{2} - 4)(3x {}^{2} - 4)[/tex]
[tex]9x {}^{4} - 24x {}^{2} + 16[/tex]
[tex]8) \\ a) \\ 5x {}^{2} + 20x + 24[/tex]
[tex]b) \\ 10x {}^{2} - 24x - 16[/tex]
[tex]c) \\ 7x {}^{2} + 20x - 5[/tex]
[tex]d) \\ - 5x {}^{2} + 36x + 13[/tex]
