Question

Решить,в классе решал,но забыл как и почему(туго с )

Answer 1

$1)3 {a}^{2} - 3 = 3( {a}^{2} - 1) = 3(a - 1)(a + 1)\\ 5 {x}^{3} - 5x = 5x( {x}^{2} - 1) = 5x(x - 1)(x + 1) \\ \\ 2)3 {a}^{2} - 6a - 3 = 3( {a}^{2} - 2a - 1) = 3(a - 1) {}^{2} \\18 {a}^{2} + 12ab + 2 {b}^{2} = 2(9 {a}^{2} + 6ab + {b}^{2}) = 2 {(3a + b)}^{2} \\ \\ 3) ( {x}^{2} + 4) {}^{2} - 16 {x}^{2} = {x}^{4} + 8 {x}^{2} + 16 - 16 {x}^{2} = {x}^{4} - 8x {}^{2} + 16 = {( {x}^{2} - 4) }^{2} \\ ({a}^{2} + c {}^{4}) {}^{2} - 4 {a}^{2} c {}^{4} = {a}^{4} + 4 {a}^{2} {c}^{4} + {c}^{8} - 4 {a}^{2} c {}^{4} = {a}^{4} + {c}^{8}$