\(\frac{8}{3}:x=\frac{16}{9}:\frac{8}{3}\)

\(\frac{8}{3}:x=\frac{16}{9}.\frac{3}{8}\)

\(\frac{8}{3}:x=\frac{2}{3}\)

       \(x=\frac{8}{3}:\frac{2}{3}\)

      \(x=\frac{8}{3}.\frac{3}{2}\)

    \(x=4\)

Vậy x = 4

\(x-1,5=\frac{2x}{3}\)

\(x=\frac{2x}{3}+1,5\)

\(\frac{3x}{3}=\frac{2x}{3}+\frac{4,5}{3}\)

\(\frac{3x}{3}=\frac{2x+4,5}{3}\)

\(3x=2x+4.5\)

\(3x-2x=4.5\)

 \(x=4,5\)

Vây x = 4,5

\(\chi-\frac{3}{2}=\frac{2}{3}x\)

\(\chi-\frac{2}{3}x=\frac{3}{2}\)

\(-\frac{1}{3}x=\frac{3}{2}\)

\(\chi=-\frac{9}{2}\)

\(x^2+5x+2=0\)

\(\Leftrightarrow x^2+2.2,5.x+6,25-4,25=0\)

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

\(\Leftrightarrow x+2,5=\pm\sqrt{4,25}\)

\(\Leftrightarrow\orbr{\begin{cases}x=\sqrt{4,25}-2,5\\x=-\sqrt{4,25}-2,5\end{cases}}\)

Vậy \(x=\pm\sqrt{4,25}-2,5\)

10 giờ 48 phút - 4 giờ 15 phút = 5 giời 3 phút

Trả lời

=5 giờ 57 phút.

Chúc bạn hok tốt #

a) \(\frac{2}{5}:\left(2x+\frac{3}{4}\right)=-\frac{7}{10}\)

=> \(2x+\frac{3}{4}=-\frac{7}{10}:\frac{2}{5}\)

=> \(2x+\frac{3}{4}=-\frac{7}{4}\)

=> \(2x=\frac{-7}{4}-\frac{3}{4}\)

=> \(2x=-\frac{5}{2}\)

=> \(x=\frac{-5}{2}:2\)

=> \(x=\frac{-5}{4}\)

b) \(\frac{x+1}{3}=\frac{2-x}{2}\)

\(\Rightarrow2\left(x+1\right)=3\left(2-x\right)\)

\(\Rightarrow2x+2=6-3x\)

\(\Rightarrow2x-3x=6-2\)

\(\Rightarrow-x=4\)

\(\Rightarrow x=4\)

c) \(\left|x-\frac{3}{5}\right|.\frac{1}{2}-\frac{1}{5}=0\)

\(\Rightarrow\left|x-\frac{3}{5}\right|.\frac{1}{2}=\frac{1}{5}\)

\(\Rightarrow\left|x-\frac{3}{5}\right|=\frac{1}{5}:\frac{1}{2}\)

\(\Rightarrow\left|x-\frac{3}{5}\right|=\frac{2}{5}\)

\(\Rightarrow\orbr{\begin{cases}x-\frac{3}{5}=\frac{2}{5}\\x-\frac{3}{5}=-\frac{2}{5}\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x=\frac{3}{5}+\frac{2}{5}\\x=\frac{3}{5}+-\frac{2}{5}\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x=1\\x=\frac{1}{5}\end{cases}}\)

Vậy \(\orbr{\begin{cases}x=1\\x=\frac{1}{5}\end{cases}}\)

d) \(x^2-4x=0\)

Ta có : \(x^2-4x=0\)

\(\Rightarrow xx-4x=0\)

\(\Rightarrow x\left(x-4\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x-4=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x=0+4\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x=4\end{cases}}\)

Vậy \(\orbr{\begin{cases}x=0\\x=4\end{cases}}\)

Ta có :

3⁵⁴ = (3²)²⁷ = 9²⁷

2⁸¹ = (2³)²⁷ = 8²⁷

Do 8²⁷ <  9²⁷ nên 2⁸¹ < 3⁵⁴.

~Study well~

#KSJ

\(a,\)\(A=\left(\frac{x-2\sqrt{3x}+3}{x-3}\right)\left(\sqrt{4x}+\sqrt{12}\right).\)

\(=\left(\frac{\left(\sqrt{x}-\sqrt{3}\right)^2}{\left(\sqrt{x}-\sqrt{3}\right)\left(\sqrt{x}+\sqrt{3}\right)}\right)\)\(.\left(2\sqrt{x}+2\sqrt{3}\right)\)

\(=\frac{\left(\sqrt{x}-\sqrt{3}\right)^22\left(\sqrt{x}+\sqrt{3}\right)}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-3\right)}\)

\(=2\left(\sqrt{x}-\sqrt{3}\right)\)

\(b,x=4-2\sqrt{3}\)\(=3-2\sqrt{3}+1=\left(\sqrt{3}-1\right)^2\)

\(\Leftrightarrow\sqrt{x}=\sqrt{\left(\sqrt{3}-1\right)^2}=\sqrt{3}-1\)

\(\Rightarrow A=2\left(\sqrt{x}-\sqrt{3}\right)=2\left(\sqrt{3}-1-\sqrt{3}\right)=2.\left(-1\right)=-2\)

1, tam giác ABC có : góc ABC + góc ACB + góc BAC = 180 (đl)

góc BAC = 70; góc ACB = 50 (gt)

=> góc ABC = 180 - 70 - 50 = 60 

BE là phân giác của góc ABC => góc ABE = 1/2.góc ABC (đl)

=> góc ABE = 1/2.60 = 30 

xét tam giác AEB có : góc AEB + góc ABE + góc BAE = 180

góc BAE = 70 (gt)

=> góc AEB = 180 - 70 - 30 = 80 

góc AEB + BEC = 180 (kb)

=> góc BEC = 180 - 80 = 100

EF là phân giác của góc BEC (gt)=> góc CEF = 1/2.góc BEC (đl)

=> góc CEF = 1/2.100 = 50

vậy_

2. 

a, góc ABC phụ góc ACB 

góc HAB phụ góc HBA 

góc ACH phụ góc CAH

b, góc ACB = góc HAB 

góc HBA = góc HAC 

\(D=\left(3x+2\right)^2-\left(3x+2\right)\left(3x-2\right)-6x\)

\(\Leftrightarrow D=\left(3x+2\right)\left(3x+2-3x+2\right)-6x\)

\(\Leftrightarrow D=4\left(3x+2\right)-6x\)

\(\Leftrightarrow D=12x+8-6x\)

\(\Leftrightarrow D=6x+8\)

Vậy giá trị của D phụ thuộc vào giá trị của biến x