Szczegółowe wyjaśnienie:
zadanie 9
[tex](2x - {5y)}^{2} = ( {2x)}^{2} - 2 \times 2x \times 5y + {(5y)}^{2} = 4 {x}^{2} - 20xy + 25 {y}^{2} \\ \ (4 x + {y)}^{2} = ( {4x})^{2} + 2 \times 4x \times y + {y}^{2} = {16x}^{2} + 8xy + {y}^{2} \\ (x - \sqrt{2} )(x + \sqrt{2} ) = {x}^{2} - ( \sqrt{2} {)}^{2} = {x}^{2} - 2 \\ (1 - \sqrt{5} {)}^{2} = {1}^{2} - 2 \times 1 \times \sqrt{5} + ( \sqrt{5} {)}^{2} = 1 - 2 \sqrt{5} + 5[/tex]
