\(1,|5x|=x-12\)

\(\Rightarrow\orbr{\begin{cases}5x=x-12\\5x=12-x\end{cases}\Rightarrow}\orbr{\begin{cases}4x=-12\\6x=12\end{cases}\Rightarrow\orbr{\begin{cases}x=-3\\x=2\end{cases}}}\)

\(2,|7-x|=5x+1\)

\(\Rightarrow\orbr{\begin{cases}7-x=5x+1\\7-x=-5x-1\end{cases}\Rightarrow}\orbr{\begin{cases}6x=6\\4x=-8\end{cases}\Rightarrow}\orbr{\begin{cases}x=1\\x=-2\end{cases}}\)

\(3,|2x-3|+x=21\)

\(\Rightarrow|2x-3|=21-x\)

\(\Rightarrow\orbr{\begin{cases}2x-3=21-x\\2x-3=x-21\end{cases}\Rightarrow}\orbr{\begin{cases}3x=24\\x=-18\end{cases}\Rightarrow}\orbr{\begin{cases}x=8\\x=-18\end{cases}}\)

\(4,|4+2x|=-4x\)

\(\Rightarrow\orbr{\begin{cases}4+2x=4x\\4+2x=-4x\end{cases}\Rightarrow}\orbr{\begin{cases}2x=4\\-6x=4\end{cases}\Rightarrow}\orbr{\begin{cases}x=2\\x=-\frac{2}{3}\end{cases}}\)

\(5,|3x-1|+2=x\)

\(\Rightarrow|3x-1|=x-2\)

\(\Rightarrow\orbr{\begin{cases}3x-1=x-2\\3x-1=2-x\end{cases}\Rightarrow\orbr{\begin{cases}2x=-1\\4x=3\end{cases}\Rightarrow}\orbr{\begin{cases}x=-\frac{1}{2}\\x=\frac{3}{4}\end{cases}}}\)

\(6,|2x-5|+x=2\)

\(\Rightarrow|2x-5|=2-x\)

\(\Rightarrow\orbr{\begin{cases}2x-5=2-x\\2x-5=x-2\end{cases}\Rightarrow\orbr{\begin{cases}3x=7\\x=3\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{7}{3}\\x=3\end{cases}}}\)

kkk^^

Nhớ dùng biểu tường "Toán " nha

    \(\frac{20+18+16+...+2+190}{53\times4+4\times79-64\times2}\)

=\(\frac{\left(20+18\right)\times10:2+190}{4\times\left(53+79-32\right)}\)

= \(\frac{190}{100}\)

= \(\frac{19}{10}\)

a, 324 + 68 - 174 + 93 + 132 

\(=\left(324-174\right)+\left(68+132\right)+93\)

\(=150+200+93\)

\(=443\)

b, 68 x 125 x 16 x 5 

\(=68x5x25x80\)

\(=1700x400\)

\(=680000\)

\(\text{A=3x^2+4x-2}\)

\(=3\left(x+\frac{2}{3}\right)^2-\frac{10}{3}\ge-\frac{10}{3}\)

Dấu ''='' xảy ra khi \(x+\frac{2}{3}=0\Rightarrow x=-\frac{2}{3}\)

Câu B mình type lỗi,sửa nha

B=4x/x²-x+4

gọi SBC là a,SC là b ta có :

a=bx3+41

a+b+41=426

(bx3+41)+b+41=426

=> bx4+82=426

bx4=426-82

bx4=344

b=344:4=86

vậy a=426-86-41=299

\(\left(-2\right)^3.\left(\frac{3}{4}-0,25\right):\left(\frac{2}{\frac{1}{4}}-\frac{1}{\frac{1}{6}}\right)\)

\(=-2^3.\frac{\frac{3}{4}-0,25}{\frac{2}{\frac{1}{4}}-\frac{1}{\frac{1}{6}}}\)

\(=-2^3.\frac{\frac{3}{4}-0,25}{2}\)

\(=-\frac{\left(\frac{3}{4}-0,25\right).2^3}{2}\)

\(=-2^2.\left(\frac{3}{4}-0,25\right)\)

= -4.0,5

= -2

\(\frac{25.\left(-2\right)^{11}-2^{12}.10}{2^4.3^2.40}\) = \(\frac{5^2.\left(2\right)^{11}-2^{11}.2.10}{2^4.3^2.40}\)= \(\frac{\left(2\right)^{11}.\left(5^2-2.10\right)}{2^4.3^2.40}\)=\(\frac{\left(2\right)^{11-4=7}.\left(5^2-2.10\right)}{3^2.40}\)=\(\frac{\left(2\right)^7.\left(5\right)}{3^2.5.8}\)=\(\frac{\left(2\right)^7}{3^2.2^3}\)=\(\frac{\left(2\right)^{7-3}}{3^2}\)=\(\frac{16}{9}\)