a: \(0.4\cdot\sqrt{0.25-\sqrt{\dfrac{1}{4}}}=0.4\cdot\sqrt{0.25-0.5}\)(đề này sai rồi bạn)

b: \(\dfrac{3}{2}+2\left(x-1\right)=-5\dfrac{1}{2}\)

\(\Leftrightarrow2\left(x-1\right)=\dfrac{-11}{2}-\dfrac{3}{2}=-7\)

\(\Leftrightarrow x-1=\dfrac{-7}{2}\)

hay \(x=-\dfrac{5}{2}\)

bài lớp mấy vậy nhìn nó khó khó

\(=\dfrac{11}{4}:\dfrac{33}{16}-0,5+\left(\dfrac{14}{5}-3\right)^2\\ =\dfrac{11}{4}\cdot\dfrac{16}{33}-\dfrac{1}{2}+\left(-\dfrac{1}{5}\right)^2\\ =\dfrac{4}{3}-\dfrac{1}{2}+\dfrac{1}{25}=\dfrac{131}{150}\)

Câu 1: D

Câu 2: A

1) ĐKXĐ: \(x\ge0\)

\(pt\Leftrightarrow2x=25\Leftrightarrow x=\dfrac{25}{2}\left(tm\right)\)

2) \(=\sqrt{\dfrac{\dfrac{1}{4}}{9}}=\dfrac{\dfrac{1}{2}}{3}=\dfrac{1}{6}\)

3) \(=\sqrt{225a^2}=15a\left(do.a\ge0\right)\)

4) \(=2y^2.\dfrac{x^2}{2\left|y\right|}=\left[{}\begin{matrix}x^2y\left(y>0\right)\\-x^2y\left(y< 0\right)\end{matrix}\right.\)

a) 1,2+3.1,3=5,1

b) 0,2+2.0,5=1,2

a) \(2\sqrt{31}=\sqrt{4.31}=\sqrt{124}>\sqrt{100}=10\\\Rightarrow2\sqrt{31}>10\)

Bài 1: 

a) \(\sqrt{1.44}+3\sqrt{1.69}=1.2+3\cdot1.3=1.2+3.9=5.1\)

b) \(\sqrt{0.04}+2\cdot\sqrt{0.25}=0.2+2\cdot0.5=1.2\)

\(=0.5\left(a-2\right)-0.2\left(a-3\right)\)

=0,5a-1-0,2a+0,6

=0,3a-0,4

a, \(32^{\dfrac{x+5}{x-7}}=0,25\cdot128^{\dfrac{x-7}{x+3}}\)

\(\Leftrightarrow2^{5\cdot\dfrac{x+5}{x-7}}=2^{-2}\cdot2^{7\cdot\left(\dfrac{x-7}{x+2}\right)}\)

\(\Leftrightarrow\dfrac{5x+25}{x-7}=-2+7\cdot\left(\dfrac{x-7}{x+3}\right)\)

\(\Leftrightarrow\dfrac{5x25}{x-7}=-2\cdot\dfrac{7x-49}{x+3}\)

\(\Leftrightarrow\dfrac{5x+25}{x-7}=\dfrac{-2x-6+7x-49}{x+3}\)

\(\Leftrightarrow\dfrac{5x+25}{x-7}=\dfrac{5x-55}{x-3}\)

\(\Rightarrow5x^2+15x+25x+75=5x^2-35x-55x+385\)

\(\Leftrightarrow130x+310=0\)

\(\Leftrightarrow x=\dfrac{31}{13}\)

Ta có:

\(\left|3\right|=3\)

\(\left|\sqrt{2}\right|=\sqrt{2}\)

\(\left|16\right|=16\)

\(\left|-19\right|=19\)

\(\left|\left(-5\right)^2\right|=\left|25\right|=25\)

\(\left|\dfrac{1}{2}\right|=\dfrac{1}{2}\)

\(\left|-\sqrt{12}\right|=\sqrt{12}\)

\(\left|0,25\right|=0,25\)

Giá trị tuyệt đối của:

`3` là `3`

`sqrt 2` là `sqrt 2`.

`16` là `16`

`-19` là `19`

`(-5)^2` là `25`

`1/2` là `1/2`

`-sqrt 12` là `sqrt 12`

`0,25` là `0,25`

\(\dfrac{6}{5}\sqrt{1\dfrac{9}{16}}-\left(-\dfrac{3}{4}\right)^2:0,25\)

\(=\dfrac{6}{5}\cdot\sqrt{\dfrac{25}{16}}-\dfrac{9}{16}:0,25\)

\(=\dfrac{6}{5}\cdot\sqrt{\left(\dfrac{5}{4}\right)^2}-\dfrac{9}{16}:\dfrac{1}{4}\)

\(=\dfrac{6}{5}\cdot\dfrac{5}{4}-\dfrac{9\cdot4}{16}\)

\(=\dfrac{6}{4}-\dfrac{9}{4}\)

\(=\dfrac{6-9}{4}\)

\(=-\dfrac{3}{4}\)