\(\left(-\dfrac{2}{3}\right).0,75+1\dfrac{2}{3}:\left(-\dfrac{4}{9}\right)+\left(-\dfrac{1}{2}\right)^2\)

\(=\left(-\dfrac{2}{3}\right).\dfrac{3}{4}+\dfrac{5}{3}:\left(-\dfrac{4}{9}\right)+\dfrac{1}{4}\)

\(=\left(-\dfrac{1}{2}\right)+\left(-\dfrac{15}{4}\right)+\dfrac{1}{4}\)

\(=-\dfrac{16}{4}=-4\)

1) 2,75 - 5/6 × 2/5 = 2,75 - (5/6) × (2/5) = 2,75 - 1/3 = 2,75 - 0,33 = 2,42

2) 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 3/4) - 3/5 = 1,25 - (5/6 - 9/12) - 3/5 = 1,25 - (10/12 - 9/12) - 3/5 = 1,25 - 1/12 - 3/5 = 1,25 - 0,08 - 0,6 = 1,25 - 0,68 = 0,57

3) 4/9 × 0,75 + 8/5 + 3,125 = (4/9) × 0,75 + 8/5 + 3,125 = 0,44 + 8/5 + 3,125 = 0,44 + 1,6 + 3,125 = 0,44 + 4,725 = 5,165

4) 1,125 - 4/7 - 0,12 = 1,125 - (4/7) - 0,12 = 1,125 - 0,57 - 0,12 = 0,435 - 0,12 = 0,315

5) (1/3 + 0,4) × 3,5 + (1/6 + 0,75) × 6/5

b) (5/2-3x)=25/9

            3x = 5/2-25/9

            3x =-5/18

              x =-5/18:3

              x=-5/54

\(e.\left(x-1\right)^5=-32\)

  \(\left(x-1\right)^5=\left(-2\right)^5\)

   \(x-1=-2\)

   \(x\)      \(=-2+1\)

   \(x\)        \(=-1\)

Vậy \(x=-1\)

Bài 2: 

a: \(\left(3x-3\right)^2-\left(5x-3\right)^2=0\)

\(\Leftrightarrow\left(3x-3-5x+3\right)\left(3x-3+5x-3\right)=0\)

\(\Leftrightarrow-2x\left(8x-6\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{3}{4}\end{matrix}\right.\)

\(\left(-0,75\right)-\left(-1+\dfrac{2}{3}\right):0,5+\left(-\dfrac{1}{4}\right)\)

\(=\left(-0,75\right)-\left(-1-\dfrac{2}{3}\right)\cdot\dfrac{1}{2}-0,25\)

\(=\left(-0,75-0,25\right)+\dfrac{5}{6}\)

\(=-1+\dfrac{5}{6}\)

\(=-\dfrac{11}{6}\)

_________________

\(\left[\left(-\dfrac{3}{2}\right)+\dfrac{2}{3}\right]^2\cdot\dfrac{24}{25}-\dfrac{1}{5}\)

\(=\left(-\dfrac{9}{6}+\dfrac{4}{6}\right)^2\cdot\dfrac{24}{25}-\dfrac{1}{5}\)

\(=\left(\dfrac{-5}{6}\right)^2\cdot\dfrac{24}{25}-\dfrac{1}{5}\)

\(=\dfrac{25}{36}\cdot\dfrac{24}{25}-\dfrac{1}{5}\)

\(=\dfrac{2}{3}-\dfrac{1}{5}\)

\(=\dfrac{7}{15}\)

lười quá

\(a,\left(-0,75\right)-\left(-1+\dfrac{2}{3}\right):0,5-\dfrac{1}{4}\\ =-\dfrac{3}{4}-\left(\dfrac{-3+2}{3}\right):\dfrac{1}{2}-\dfrac{1}{4}\\ =-\dfrac{3}{4}-\left(-\dfrac{1}{3}\right):\dfrac{1}{2}-\dfrac{1}{4}\\ =-\dfrac{3}{4}-\left(-\dfrac{1}{3}\right)\times2-\dfrac{1}{4}\\ =-\dfrac{3}{4}+\dfrac{2}{3}-\dfrac{1}{4}\\ =\left(-\dfrac{3}{4}-\dfrac{1}{4}\right)+\dfrac{2}{3}\\ =-\dfrac{4}{4}+\dfrac{2}{3}\\ =-1+\dfrac{2}{3}\\ =\dfrac{-3+2}{3}=-\dfrac{1}{3}\)

\(b,\left[\left(-\dfrac{3}{2}\right)+\dfrac{2}{3}\right]^2\times\dfrac{24}{25}-\dfrac{1}{5}\\ =\left(\dfrac{-3\times3+2\times2}{6}\right)^2\times\dfrac{24}{25}-\dfrac{1}{5}\\ =\left(-\dfrac{5}{6}\right)^2\times\dfrac{24}{25}-\dfrac{1}{5}\\ =\dfrac{25}{36}\times\dfrac{24}{25}-\dfrac{1}{5}\\ =\dfrac{2}{3}-\dfrac{1}{5}\\ =\dfrac{2\times5-3}{15}=\dfrac{7}{15}\)

1/9 - 0,3 . 5/9 + 1/3 + 5

= 1/9 - 3/10 . 5/9 + 1/3 + 5

= 1/9 - 1/6 + 16/3

= -1/18 + 16/3

= 95/18

\(\sqrt{0,36}-\left|-0,75\right|:\left(-1\dfrac{3}{4}\right)\\ =0,6-0,75:\dfrac{-7}{4}\\ =\dfrac{3}{5}-\dfrac{3}{4}\cdot\dfrac{-4}{7}\\ =\dfrac{3}{5}-\dfrac{-12}{28}\\ =\dfrac{3}{5}+\dfrac{3}{7}\\ =\dfrac{36}{35}\)

\(1-\left(\dfrac{5}{9}-\dfrac{2}{3}\right)^2:\dfrac{4}{27}\\ =1-\left(\dfrac{5}{9}-\dfrac{6}{9}\right)^2\cdot\dfrac{27}{4}\\ =1-\left(-\dfrac{1}{9}\right)^2\cdot\dfrac{27}{4}\\ =1-\dfrac{1}{81}\cdot\dfrac{27}{4}\\ =1-\dfrac{1}{12}\\ =\dfrac{11}{12}\)