a)
[tex] {6}^{2} + 7 {}^{2} = (6 + 7) {}^{2} \\ 6 {}^{2} + 7 { }^{2} = 6 {}^{2} + 2 \times 6 \times 7 + {7}^{2} \\ 6 {}^{2} + 7 {}^{2} = 6 {}^{2} + 84 + 7 {}^{2} \\ 6 {}^{2} + 7 {}^{2} - 6 {}^{2} - 7 {}^{2} = 84 \\ 0 = 84[/tex]
FALS!!!
FORMULA FOLOSITĂ:
( a + b ) ² = a² + 2ab + b²
b)
[tex] {11}^{3} - {10}^{3} = (11 - 10) {}^{3} \\ {11}^{3} - 10 {}^{3} = {11}^{3} - 3 \times 11 {}^{2} \times 10 + 3 \times 11 \times {10}^{2} - {10}^{3} \\ {11}^{3} - 10 {}^{3} = 11 {}^{3} - 3 \times 121 \times 10 + 3 \times11 \times 100 - {10}^{3} \\ 11 {}^{3} - 10 {}^{3} = 11 {}^{3} - 123 + 3300 - {10}^{3} \\ 11 {}^{3} - 10 {}^{3} - 11 {}^{3} + 10 {}^{3} = 3300 - 123 \\ 0 = 3177[/tex]
FALS!!!
FORMULA FOLOSITĂ:
( a - b ) ³ = a³ - 3a²b + 3ab² - b³
