Question

найдите значение выражения: ​

Answer 1

▪а)

$125 - (5 - 3x)(25 + 15x + 9 {x}^{2} ) = 125 - ({5}^{3} - {(3x)}^{3} ) = 125 - 125 + 27 {x}^{3} = 27 \times {( - \frac{ 4}{3}) }^{3} = - \frac{ {3}^{3} \times {4}^{3} }{ {3}^{3} } = - {4}^{3} = - 64$

▪б)

$25 - (2 - 3a)(4 + 6a + 9 {a}^{2} ) = 25 - 8 + 27 {a}^{3} = 17 + 27 {a}^{3} = 17 + 27 \times {( - \frac{1}{3}) }^{3} = 17 - \frac{ {3}^{3} }{ {3}^{3} } = 17 - 1 = 16$

▪в)

$127 + (5c - 3)(25 {c}^{2} + 15c + 9) = 127 + 125 {c}^{3} - 27 = 100 + 125 {c}^{3} = 100 + 125 \times {( - 1 \frac{1}{5} )}^{3} = 100 + {5}^{3} \times ( - \frac{6}{5} ) ^{3} = 100 - 216 = - 116$

▪г)

$64 - (4 - 3a)(16 + 12a + 9 {a}^{2} ) = 64 - (64 - 27 {a}^{3} ) = 64 - 64 + 27 {a}^{3} = 27 {a}^{3} = 27 \times {( - \frac{2}{3}) }^{3} = - \frac{ {3}^{3} \times {2}^{3} }{ {3}^{3} } = - 8$