Question

ПООООЖАЛУЙСЬА РЕШИТЕ,ОЧЕНЬ НУЖНО,ЧЕМ БЫСТРЕЕ ТЕМ ЛУЧШЕ(в течение урока)

Answer 1

▪1)

$(a - 4) ^{2} - 2a(5a - 4) = {a}^{2} - 8a + 16 - 10 {a}^{2} + 8a = 16- 9 {a}^{2} = (4 - 3a)(4 + 3a) = (4 + \frac{3}{3} )(4 - \frac{3}{3} ) = 5 \times 3 = 15$

▪2)

$(4d - 3)(4d + 3) - {(4d + 3)}^{2} = (4d + 3)(4d - 3 - 4d - 3) = (4d + 3) \times (-6) = - 6 \times (4 \times 50 + 3) = - 6 \times (200 + 3) = - 1200 - 18 = - 1218$

▪3)

$\frac{9}{x} - \frac{9}{5x} = \frac{45 - 9}{5x} = \frac{36}{5x} = \frac{36}{5 \times ( - 2)} = - \frac{ 36}{10} = - 3.6$

▪4)

$\frac{1}{4x} - \frac{4x + y}{4xy} = \frac{y - 4x - y}{4xy} = - \frac{4x}{4xy} = - \frac{1}{y} = - \frac{1}{ \frac{1}{6} } = - 6$

▪5)

$(x + 1) \div \frac{ {x}^{2} + 2x + 1 }{x - 1} = \frac{(x + 1)(x - 1)}{ {(x + 1)}^{2} } = \frac{x - 1}{x + 1} = \frac{4 - 1}{4 + 1} = \frac{3}{5} = 0.6$

▪6)

$\frac{a + x}{a} \div \frac{ax + {x}^{2} }{ {a}^{2} } = \frac{(a + x) \times {a}^{2} }{a \times x(a + x)} = \frac{a}{x} = \frac{56}{40} = \frac{7}{5} = 1 \frac{2}{5} = 1.4$

▪7)

$\frac{a - 5x}{a} \div \frac{ax - 5 {x}^{2} }{ {a}^{2} } = \frac{(a - 5x) \times {a}^{2} }{a \times x(a - 5x)} = \frac{a}{x} = \frac{ - 74}{ - 10} = 7.4$

▪8)

$3b - \frac{3 {b}^{2} - a}{b} = \frac{3 {b}^{2} - 3 {b}^{2} + a}{b} = \frac{a}{b} = \frac{ - 79}{ - 2} = 39.5$

▪9)

$\frac{ {a}^{2} - 81 }{2 {a}^{2} - 18a } = \frac{(a - 9)(a + 9)}{2a(a - 9)} = \frac{a + 9}{2a} = \frac{1.5 + 9}{2 \times 1.5} = \frac{10.5}{3} = \frac{7}{2} = 3.5$

▪10)

$\frac{ {a}^{2} - 9 {b}^{2} }{3ab} \div (\frac{1}{3b} - \frac{1}{a} ) = \frac{(a - 3b)(a + 3b)}{3ab} \div \frac{a - 3b}{3ab} = \frac{(a - 3b)(a + 3b) \times 3ab}{3ab \times (a - 3b)} = a + 3b = 2 \frac{2}{17} +3 \times 9 \frac{5}{17} = 2 \frac{2}{17} + 27 \frac{5 \times 3}{17} = 2 \frac{2}{17} + 27 \frac{15}{17} = 29 \frac{2 + 15}{17} = 29 \frac{17}{17} = 30$