2.b/ \(-\frac{25}{35}=-\frac{5}{7}=-0,714...\)

             \(x\) 

             \(\left(-2\right)^2=4\)

\(x\in\left\{0;1;2;3\right\}\)

e ) \(\left|x-\frac{2}{3}\right|+0,25=\frac{3}{4}\)

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

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

    x           =7/6                         x         = 1/6

O x y 50 z 100

Ta có : xoy = yoz = xoz / 2 = 100 / 2 = 50

=> Oy là tia phân giác 

Hơi gọn chút

b) \(\left|x+2\right|+\left|y+5\right|=0\)

Ta có :

\(\left|x+2\right|\ge0\)

\(\left|y+5\right|\ge0\)

\(\Rightarrow\left|x+2\right|+\left|y+5\right|\ge0\)

Mà đề cho \(\left|x+2\right|+\left|y+5\right|=0\)

\(\Rightarrow\hept{\begin{cases}\left|x+2\right|=0\\\left|y+5\right|=0\end{cases}\Rightarrow\hept{\begin{cases}x+2=0\\y+5=0\end{cases}\Rightarrow}\hept{\begin{cases}x=-2\\y=-5\end{cases}}}\)

(x + 2)(y - 3) = 5 = 1.5 = 5.1 = (-1).(-5) = (-5).(-1)

Xét 4 trường hợp , ta có :

\(\left(1\right)\hept{\begin{cases}x+2=1\\y-3=5\end{cases}\Rightarrow\hept{\begin{cases}x=-1\\y=8\end{cases}}}\)

\(\left(2\right)\hept{\begin{cases}x+2=5\\y-3=1\end{cases}}\Rightarrow\hept{\begin{cases}x=3\\y=4\end{cases}}\)

\(\left(3\right)\hept{\begin{cases}x+2=-1\\y-3=-5\end{cases}}\Rightarrow\hept{\begin{cases}x=-3\\y=-2\end{cases}}\)

\(\left(4\right)\hept{\begin{cases}x+2=-5\\y-3=-1\end{cases}}\Rightarrow\hept{\begin{cases}x=-7\\y=2\end{cases}}\)

khó quá

a. Vì \(\left|x-y-5\right|\ge0\forall x;y;2019\left|y-3\right|^{2020}\ge0\forall y\)

\(\Rightarrow\left|x-y-5\right|+2019\left|y-3\right|^{2020}\ge0\)

Dấu "=" xảy ra \(\Leftrightarrow\orbr{\begin{cases}\left|x-y-5\right|=0\\2019\left|y-3\right|^{2020}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x-y-5=0\\y-3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x-y=5\\y=3\end{cases}}\)

b. \(2\left(x-5\right)^4\ge0\forall x;5\left|2y-7\right|^5\ge0\forall y\)

\(\Rightarrow2\left(x-5\right)^4+5\left|2y-7\right|^5\ge0\)

Dấu "=" xảy ra \(\Leftrightarrow\orbr{\begin{cases}2\left(x-5\right)^4=0\\5\left|2y-7\right|^5=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x-5=0\\2y-7=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=5\\y=\frac{7}{2}\end{cases}}\)

1)

B(37) = {0; 37; 74; 111;...}

2)

Ư(7) = {1; 7}

Ư(9) = {1; 3; 9}

Ư(10) = {1; 2; 5; 10}

Ư(16) = {1; 2; 4; 8; 16}

Ư(18) = {1; 2; 3; 5; 9; 18}

Ư(20) = {1; 2; 4; 5; 10; 20}

3)1) x = {0; 26; 39;52}

   2) x = {0; 17; 34; 51}

   3) x = {0; 12; 24; 36; 48;...}

   4) x = {1; 2; 3; 5; 6; 10; 15; 30}

   5) x = {0; 7; 14; 21; 28; 35; 42;49} 

Sai thì thôi nha

HỌC TỐT!!!

a) \(\left(x+2\right)\left(y-3\right)=5\)

Ta có bảng sau:

Vậy cặp số \(\left(x;y\right)\) là \(\left(-1;8\right);\left(3;4\right);\left(-3;-2\right);\left(-7;2\right)\)

b) \(\left|x+2\right|+\left|y+5\right|=0\)

\(\Rightarrow\left[\begin{matrix}\left|x+2\right|=0\\\left|y+5\right|=0\end{matrix}\right.\Rightarrow\left[\begin{matrix}x+2=0\\y+5=0\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=-2\\y=-5\end{matrix}\right.\)

Vậy \(x=-2;y=-5\)

c) tương tự b

d) sai đề

d)x\(\in\varnothing\)

c: \(\left|\dfrac{7}{5}x+\dfrac{2}{3}\right|=\left|\dfrac{4}{3}x-\dfrac{1}{4}\right|\)

=>7/5x+2/3=4/3x-1/4 hoặc 7/5x+2/3=1/4-4/3x

=>1/15x=-11/12 hoặc 41/15x=-5/12

=>x=-55/4 hoặc x=-25/164

d: |7/8x+5/6|=|1/2x+5|

=>|42x+40|=|24x+240|

=>42x+40=24x+240 hoặc 42x+40=-24x-240

=>18x=200 hoặc 66x=-280

=>x=100/9 hoặc x=-140/33

a, \(x^2-9=0\Rightarrow x^2=9\Rightarrow x\pm3\)

b, \(\left(x-3\right)^2-25=0\Rightarrow\left(x-3\right)^2=25\)

\(\Rightarrow\left\{{}\begin{matrix}x-3=5\\x-3=-5\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=8\\x=-2\end{matrix}\right.\)

c, \(\left(x-3\right)\left(2x-5\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-3=0\\2x-5=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\\2x=5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{5}{2}\end{matrix}\right.\)

d, \(\left(x-3\right)x-2\left(x-3\right)=0\)

\(\Rightarrow\left(x-3\right)\left(x-2\right)=0\)

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

e, \(3x\left(x-1\right)-5\left(1-x\right)=0\)

\(\Rightarrow3x\left(x-1\right)+5\left(x-1\right)=0\)

\(\Rightarrow\left(x-1\right)\left(3x+5\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-1=0\\3x+5=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=1\\x=-\dfrac{5}{3}\end{matrix}\right.\)

g, \(x^2+6x-7=0\)

\(\Rightarrow x^2-x+7x-7=0\)

\(\Rightarrow x.\left(x-1\right)+7.\left(x-1\right)=0\)

\(\Rightarrow\left(x-1\right)\left(x+7\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-1=0\\x+7=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=1\\x=-7\end{matrix}\right.\)

h,\(2x^2+5x-7=0\)

\(\Rightarrow2x^2-2x+7x-7=0\)

\(\Rightarrow2x.\left(x-1\right)+7.\left(x-1\right)=0\)

\(\Rightarrow\left(x-1\right)\left(2x+7\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-1=0\\2x+7=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=1\\x=-\dfrac{7}{2}\end{matrix}\right.\)

Chúc bạn học tốt!!!

a) \(x^2-9=0\Leftrightarrow x^2=9\Leftrightarrow\left\{{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\) vậy \(x=3;x=-3\)

b) \(\left(x-3\right)^2-25=0\Leftrightarrow\left(x-3\right)^2=25\Leftrightarrow\left\{{}\begin{matrix}x-3=5\\x-3=-5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=8\\x=-2\end{matrix}\right.\)

vậy \(x=8;x=-2\)

c) \(\left(x-3\right)\left(2x-5\right)=0\Leftrightarrow\left\{{}\begin{matrix}x-3=0\\2x-5=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=3\\x=\dfrac{5}{2}\end{matrix}\right.\)

vậy \(x=3;x=\dfrac{5}{2}\)

d)\(\left(x-3\right).x-2\left(x-3\right)=0\Leftrightarrow\left(x-2\right)\left(x-3\right)=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x-2=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\x=3\end{matrix}\right.\) vậy \(x=2;x=3\)

e) \(3x\left(x-1\right)-5\left(1-x\right)=0\Leftrightarrow\left(3x+5\right)\left(x-1\right)=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}3x+5=0\\x-1=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{-5}{3}\\x=1\end{matrix}\right.\) vậy \(x=\dfrac{-5}{3};x=1\)

câu e t thấy sai sai nhưng vẫn làm ; bn coi lại đề nha

g) \(x^2+6x-7=0\Leftrightarrow x^2-x+7x-7=0\)

\(\Leftrightarrow x\left(x-1\right)+7\left(x-1\right)=0\Leftrightarrow\left(x+7\right)\left(x-1\right)=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x+7=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-7\\x=1\end{matrix}\right.\) vậy \(x=-7;x=1\)

h) \(2x^2+5x-7=0\Leftrightarrow2x^2-2x+7x-7=0\)

\(\Leftrightarrow2x\left(x-1\right)+7\left(x-1\right)=0\Leftrightarrow\left(2x+7\right)\left(x-1\right)=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}2x+7=0\\x-1=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{-7}{2}\\x=1\end{matrix}\right.\) vậy \(x=\dfrac{-7}{2};x=1\)

|\(\frac32x\) + \(\frac12\)| = |4\(x\) - 1|

\(\left[\begin{array}{l}\frac32x+\frac12=-4x+1\\ \frac32x+\frac12=4x-1\end{array}\right.\)

\(\left[\begin{array}{l}\frac32x+4x=1-\frac12\\ \frac32x-4x=-1-\frac12\end{array}\right.\)

\(\left[\begin{array}{l}\frac{11}{2}x=\frac12\\ -\frac52x=-\frac32\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac12:\frac{11}{2}\\ x=-\frac32:\frac{-5}{2}\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac12\times\frac{2}{11}\\ x=-\frac32\times\frac{-2}{5}\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac{1}{11}\\ x=\frac35\end{array}\right.\)

Vậy \(x\in\) {\(\frac{1}{11};\frac35\)}

|\(\frac54x\) - \(\frac72\)| - |\(\frac58x\) + \(\frac35\)| = 0

|\(\frac54x\) - \(\frac72\)| = |\(\frac58x\) + \(\frac35\)|

\(\left[\begin{array}{l}\frac54x-\frac72=-\frac58x-\frac35\\ \frac54x-\frac72=\frac58x+\frac35\end{array}\right.\)

\(\left[\begin{array}{l}\frac54x+\frac58x=\frac72-\frac35\\ \frac54x-\frac58x=\frac72+\frac35\end{array}\right.\)

\(\left[\begin{array}{l}\frac{15}{8}x=\frac{29}{20}\\ \frac58x=\frac{41}{10}\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac{29}{10}:\frac{15}{8}\\ x=\frac{41}{10}:\frac58\end{array}\right.\)

\(\left[\begin{array}{l}x=\frac{116}{75}\\ x=\frac{164}{25}\end{array}\right.\)

Vậy \(x\in\) {\(\frac{116}{75}\); \(\frac{164}{25}\)}

đúng rồi bạn

đúng òi đó

a) \(\frac{9}{20}\)                                                   c) \(\frac{-55}{4}\)                                                                                                                                 

b) \(\frac{116}{75}\)                                                d) \(\frac{-76}{45}\)

đúng hết đấy nhé mình tính kĩ lắm ko sai đâu

       chúc may mắn