a: \(A=\left|-1+2+4\right|=\left|5\right|=5\)

b: \(B=\left|-0.25\right|+\left|-0.25-1\right|+\left|-0.25-2\right|\)

\(=0.25+1.25+2.25\)

=3.75

Bài 2: 

a: \(\left(0.25\right)^3\cdot32=\dfrac{1}{4^3}\cdot32=\dfrac{32}{64}=\dfrac{1}{2}\)

b: \(\left(-0.125\right)^3\cdot80^4=\left(-0.125\cdot80\right)^3\cdot80=-80\)

c: \(\dfrac{8^2\cdot4^5}{2^{20}}=\dfrac{2^6\cdot2^{10}}{2^{20}}=\dfrac{1}{2^4}=\dfrac{1}{16}\)

d: \(\dfrac{81^{11}\cdot3^{17}}{27^{10}\cdot9^{15}}=\dfrac{3^{44}\cdot3^{17}}{3^{30}\cdot3^{30}}=\dfrac{3^{61}}{3^{60}}=3\)

E, F, G, H, I tí nữa Thầy rảnh Thầy giải giúp nhé!

a) \(3,6-\left|x-0,4\right|=0\)

\(\Leftrightarrow\left|x-0,4\right|=3,6\)

\(\Leftrightarrow\left[{}\begin{matrix}x-0,4=3,6\\x-0,4=-3,6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-3,2\end{matrix}\right.\)

Vậy \(x\in\left\{4;-3,2\right\}\)

b) Ta có:

\(\frac{x}{2}=y=\frac{z}{3}=\frac{2y}{2}=\frac{x-2y+z}{2-2+3}=\frac{210}{3}=70\)

\(\Rightarrow\left\{{}\begin{matrix}\frac{x}{2}=70\\y=70\\\frac{z}{3}=70\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=140\\y=70\\z=210\end{matrix}\right.\)

Vậy \(x=140\); \(y=70\); \(z=210\)

c)\(\left|x+0,25\right|-4=\frac{1}{4}\)

\(\Leftrightarrow\left|x+\frac{1}{4}\right|=\frac{17}{4}\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\frac{1}{4}=\frac{17}{4}\\x+\frac{1}{4}=\frac{-17}{4}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=\frac{-9}{2}\end{matrix}\right.\)

Vậy \(x\in\left\{4;\frac{-9}{2}\right\}\)

d) \(x:\left(0,25\right)^4=\left(0,5\right)^2\)

\(\Leftrightarrow x=\left(0,25\right)^4.\left(0,5\right)^2\)

\(\Leftrightarrow x=\left(0,5\right)^8.\left(0,5\right)^2\)

\(\Leftrightarrow x=\left(0,5\right)^{10}=\left(\frac{1}{2}\right)^{10}=\frac{1}{2^{10}}=\frac{1}{1024}\)

Vậy \(x=\frac{1}{1024}\)

e) \(3^{x-1}+5.3^{x-1}=162\)

\(\Leftrightarrow6.3^{x-1}=162\)

\(\Leftrightarrow3^{x-1}=27\)

\(\Leftrightarrow3^{x-1}=3^3\)

\(\Leftrightarrow x-1=3\)

\(\Leftrightarrow x=4\)

f) \(\frac{x}{-25}=\frac{2}{5}\)

\(\Leftrightarrow x=\left(-25\right).\frac{2}{5}=-10\)

Vậy \(x=-10\)

g) \(\left|x+\frac{3}{4}\right|-\frac{3}{4}=\sqrt{\frac{1}{9}}\)

\(\Leftrightarrow\left|x+\frac{3}{4}\right|-\frac{3}{4}=\frac{1}{3}\)

\(\Leftrightarrow\left|x+\frac{3}{4}\right|=\frac{13}{12}\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\frac{3}{4}=\frac{13}{12}\\x+\frac{3}{4}=-\frac{13}{12}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{1}{3}\\x=-\frac{11}{6}\end{matrix}\right.\)

Vậy \(x\in\left\{\frac{1}{3};-\frac{11}{6}\right\}\)

a) \(3,6-\left|x-0,4\right|=0\)

\(\Rightarrow\left|x-0,4\right|=3,6-0\)

\(\Rightarrow\left|x-0,4\right|=3,6.\)

\(\Rightarrow\left[{}\begin{matrix}x-0,4=3,6\\x-0,4=-3,6\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3,6+0,4\\x=\left(-3,6\right)+0,4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-3,2\end{matrix}\right.\)

Vậy \(x\in\left\{4;-3,2\right\}.\)

c) \(\left|x+0,25\right|-4=\frac{1}{4}\)

\(\Rightarrow\left|x+\frac{1}{4}\right|=\frac{1}{4}+4\)

\(\Rightarrow\left|x+\frac{1}{4}\right|=\frac{17}{4}.\)

\(\Rightarrow\left[{}\begin{matrix}x+\frac{1}{4}=\frac{17}{4}\\x+\frac{1}{4}=-\frac{17}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{17}{4}-\frac{1}{4}\\x=\left(-\frac{17}{4}\right)-\frac{1}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-\frac{9}{2}\end{matrix}\right.\)

Vậy \(x\in\left\{4;-\frac{9}{2}\right\}.\)

d) \(x:\left(0,25\right)^4=\left(0,5\right)^2\)

\(\Rightarrow x:\left(0,25\right)^4=0,25\)

\(\Rightarrow x=\left(0,25\right).\left(0,25\right)^4\)

\(\Rightarrow x=\left(0,25\right)^5\)

\(\Rightarrow x=\frac{1}{1024}\)

Vậy \(x=\frac{1}{1024}.\)

Chúc bạn học tốt!

2 í tách riêng hay chung vậy bạn ?

a,=11/12 x 8/15 - 1/6:2

  = 22/45-1/2

  = 73/180

b, =9/4:0.01 

   = 225

K nha

0,25 x 40

= 10

....

Cái chỗ phần b là ( 2 và 1/4 - 0,25 ) :0,01 phần 0,25x 40 nhé mn

Đáp án B

\(a,x+0,25=\dfrac{5}{4}\\ x+\dfrac{1}{4}=\dfrac{5}{4}\\ x=\dfrac{5}{4}-\dfrac{1}{4}\\ x=1\\ b,\left(3-2x\right)-3=3\\ 3-2x=3+3\\ 3-2x=6\\ 2x=3-6\\ 2x=-3\\ x=-\dfrac{3}{2}\\ c,\left(x-1\right)^5=-32\\ \left(x-1\right)^5=\left(-2\right)^5\\ \Rightarrow x-1=-2\\ x=-2+1\\ x=-1\\ d,0,2:\dfrac{6}{5}=\dfrac{2}{3}:\left(6x+7\right)\\ \dfrac{1}{5}:\dfrac{6}{5}=\dfrac{1}{9}x+\dfrac{2}{21}\\ \dfrac{1}{9}x+\dfrac{2}{21}=\dfrac{1}{6}\\ \dfrac{1}{9}x=\dfrac{1}{6}-\dfrac{2}{21}\\ \dfrac{1}{9}x=\dfrac{1}{14}\\ x=\dfrac{1}{14}:\dfrac{1}{9}\\ x=\dfrac{9}{14}\)

Các câu sau làm tương tự nhé! ( mỏi tay lắm)

e, Áp dụng tính chất của dãy tỉ số bằng nhau, ta có:

\(\dfrac{x}{3}=\dfrac{y}{4}=\dfrac{x-y}{3-4}=\dfrac{12}{-1}=-12\\ \Rightarrow\left\{{}\begin{matrix}x=-12\cdot3=-36\\y=-12\cdot4=-48\end{matrix}\right.\)

g, Ta có : \(\dfrac{x}{19}=\dfrac{y}{21}=\dfrac{2x}{38}=\dfrac{y}{21}\)

Áp dụng tính chất của dãy tỉ số bằng nhau, ta có:

\(\dfrac{2x}{38}=\dfrac{y}{21}=\dfrac{2x-y}{38-21}=\dfrac{34}{17}=2\\ \Rightarrow\left\{{}\begin{matrix}x=\dfrac{2\cdot38}{2}=38\\y=2\cdot21=42\end{matrix}\right.\)

H, Thiếu đề.

Tiện tay làm luôn