Question

Решите пожалуйста мне срочно

Answer 1

$1) = \frac{5.6( {5.5}^{2} - {4.5}^{2} )}{2.8( {7.2}^{2} - {2.8}^{2} ) } = \frac{2(5.5 - 4.5)(5.5 + 4.5)}{(7.2 - 2.8)(7.2 + 2.8)} = \frac{2 \times 1 \times 10}{4.4 \times 10} = \frac{20}{44} = \frac{5}{11}$
$2) {x}^{2} (x + 5) - 25(x + 5) = 0 \\ (x + 5)( {x}^{2} - 25) = 0 \\ (x + 5)(x + 5)(x - 5) = 0 \\ x + 5 = 0 \: \: \: \: \: \: \: \: \: \: \: \: \: \: x - 5 = 0 \\ x = - 5 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: x = 5$
$3) a) = (5y - a)(5y + a) \\ b) = (c + 2b)(c + 2b)$
$4) 12 - 16 + 8x - {x}^{2} = 3x - {x}^{2} \\ 3x - {x}^{2} + {x}^{2} - 8x = - 4 \\ - 5x = - 4 \\ x = \frac{4}{5} = 0.8$
$5) a) \: = 9 {x}^{2} - {y}^{4} \\ b) = {a}^{6} - 12 {a}^{4} + 36 {a}^{2} \\ c) = (a - x)(x + a)(a - x)(x + a) = ( {a}^{2} - {x}^{2} )( {a}^{2} - {x}^{2} ) = {a}^{4} - 2 {a}^{2} {x}^{2} + {x}^{4}$
$6) a) 16 {x}^{2} - 9 - 16 {x}^{2} + 8x - 1 = 3x \\ 8x - 3x = 10 \\ 5x = 10 \\ x = 2 \\ b) (4c - 7)(4c + 7) = 0 \\ 4c - 7 = 0 \: \: \: \: \: \: \: \: \: 4c + 7 = 0 \\ 4c = 7 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: 4c = - 7 \\ c = \frac{7}{4} = 1 \frac{3}{4} \: \: \: \: \: \: c = - \frac{7}{4} = - 1 \frac{3}{4}$
$7)a) = (10 {a}^{2} - \frac{1}{3} b)(10 {a}^{2} + \frac{1}{3} b) \\ b) = (3x + x - 1)(3x - x + 1) = (4x - 1)(2x + 1)$