Réponse:
[tex]a = (7x - 3)(7x + 3) - (8x + 5)(8x - 5) \\ = 49x ^{2} - 9 - (64 {x}^{2} - 25) \\ = 49 {x}^{2} - 9 - 64 {x}^{2} + 25 \\ = - 15 {x}^{2} + 16[/tex]
[tex](3x - 5)(3x + 5) - (3x + 5) ^{2} \\ = 9 {x}^{2} - 25 - (9 {x}^{2} + 30x + 25) \\ = 9 {x}^{2} - 25 - 9 {x}^{2} - 30x - 25 \\ = - 50 - 30x \\ = - 10( 3x - 5)[/tex]
[tex]c = {x}^{2} + 6x + 9 - (x + 3)(x - 2) \\ = {x}^{2} + 6x + 9 - ( {x}^{2} - 2x + 3x - 6) \\ = {x}^{2} + 6x + 9 - ( {x}^{2} + x - 6) \\ = {x}^{2} + 6x + 9 - {x}^{2} - x + 6 \\ = 5x + 15 = 5(x + 3)[/tex]
[tex]d = ( \sqrt{2} + \sqrt{3} )( \sqrt{2} - \sqrt{3} ) \\ = ( \sqrt{2 } ^{2} ) - ( { \sqrt{3} }^{2} ) \\ = 2 - 3 \\ = - 1[/tex]
[tex](3 \sqrt{2} + 1) ^{2} \\ = 18 + 6 \sqrt{2} + 1 \\ = 19 + 6 \sqrt{2} [/tex]
