Mình ko ghi lại đề , bạn ghi ra xong rồi suy ra như mình nha .

1) \(=>A=\left(6x^2+3x-10x-5\right)-\left(6x^2+14x-9x-21\right)\)

\(=>A=-12x+16\)

2) \(=>B=8x^3+27-8x^3+2=29\)

3)\(=>C=[\left(x-1\right)-\left(x+1\right)]^3=\left(-2\right)^3=-8\)

4)\(=>D=[\left(2x+5\right)-\left(2x\right)]^3=5^3=125\)

5)\(=>E=\left(3x+1\right)^2-\left(3x+5\right)^2+12x+2\left(6x+3\right)\)

\(=>E=\left(3x+1+3x+5\right)\left(3x+1-3x-5\right)+12x+12x+6\)

\(=>E=\left(6x+6\right)\left(-4\right)+24x+6=-24x-24+24x+6=-18\)

6)\(=>F=\left(2x^2+3x-10x-15\right)-\left(2x^2-6x\right)+x+7=-8\)

k cho mik nha , 

3:

a: =>x=0 hoặc x+5=0

=>x=0 hoặc x=-5

b: =>x^2=4

=>x=2 hoặc x=-2

c: =>(x-5)(2x+1+x+6)=0

=>(x-5)(3x+7)=0

=>x=5 hoặc x=-7/3

1.

a. 2x - 6 > 0 

\(\Leftrightarrow\)  2x  > 6

\(\Leftrightarrow\)    x  > 3

S = \(\left\{x\uparrow x>3\right\}\) 

b. -3x + 9 > 0

\(\Leftrightarrow\)  - 3x   > - 9 

\(\Leftrightarrow\)      x < 3

S = \(\left\{x\uparrow x< 3\right\}\) 

c. 3(x - 1) + 5 > (x - 1) + 3

\(\Leftrightarrow\) 3x - 3 + 5 > x - 1 + 3

\(\Leftrightarrow\) 3x - 3 + 5 - x + 1 - 3 > 0

\(\Leftrightarrow\) 2x > 0 

\(\Leftrightarrow\)   x > 0

S = \(\left\{x\uparrow x>0\right\}\) 

d. \(\dfrac{x}{3}-\dfrac{1}{2}>\dfrac{x}{6}\) 

\(\Leftrightarrow\dfrac{2x}{6}-\dfrac{3}{6}>\dfrac{x}{6}\)

\(\Leftrightarrow2x-3>x\)

\(\Leftrightarrow2x-3-x>0\)

\(\Leftrightarrow x-3>0\)

\(\Leftrightarrow x>3\)

\(S=\left\{x\uparrow x>3\right\}\)

2.

a. 

Ta có: a > b

3a > 3b (nhân cả 2 vế cho 3)

3a + 7 > 3b + 7 (cộng cả 2 vế cho 7)

b. Ta có: a > b

a > b (nhân cả 2 vế cho 1)

a + 3 > b + 3 (cộng cả 2 vế cho 3) (1)

Ta có; 3 > 1

b + 3 > b + 1 (nhân cả 2 vế cho 1b) (2)

Từ (1) và (2) \(\Rightarrow\) a + 3 > b + 1 

c.

5a - 1 + 1 > 5b - 1 + 1 (cộng cả 2 vế cho 1)

5a . \(\dfrac{1}{5}\) > 5b . \(\dfrac{1}{5}\) (nhân cả 2 vế cho \(\dfrac{1}{5}\) )

a > b

3.

a. 2x(x + 5) = 0

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

\(S=\left\{0,-5\right\}\)

b. x² - 4 = 0 

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

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

\(S=\left\{0,4\right\}\)

d. (x - 5)(2x + 1) + (x - 5)(x + 6) = 0

\(\Leftrightarrow\left(x-5\right)\left(2x+1+x+6\right)=0\)

\(\Leftrightarrow\left(x-5\right)\left(3x+7\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-5=0\\3x+7=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{-7}{3}\end{matrix}\right.\)

\(S=\left\{5,\dfrac{-7}{3}\right\}\)

Giúp vs ạ mk đag cần

.

a: Ta có: \(8x+11-3=5x+x-3\)

\(\Leftrightarrow8x+8=6x-3\)

\(\Leftrightarrow2x=-11\)

hay \(x=-\dfrac{11}{2}\)

b: Ta có: \(2x\left(x+2\right)^2-8x^2=2\left(x-2\right)\left(x^2+2x+4\right)\)

\(\Leftrightarrow2x\left(x^3+6x^2+12x+8\right)-8x^2=2\left(x^3-8\right)\)

\(\Leftrightarrow2x^4+12x^3+24x^2+16x-8x^2-2x^3+16=0\)

\(\Leftrightarrow2x^4+10x^3+16x^2+16x+16=0\)

\(\Leftrightarrow2x^4+4x^3+6x^3+12x^2+4x^2+8x+8x+16=0\)

\(\Leftrightarrow\left(x+2\right)\left(2x^3+6x^2+4x+8\right)=0\)

\(\Leftrightarrow x+2=0\)

hay x=-2

c: Ta có: \(\left(x+1\right)\left(2x-3\right)=\left(2x-1\right)\left(x+5\right)\)

\(\Leftrightarrow2x^2-3x+2x-3-2x^2-10x+x+5=0\)

\(\Leftrightarrow-10x+2=0\)

\(\Leftrightarrow-10x=-2\)

hay \(x=\dfrac{1}{5}\)

d: Ta có: \(\dfrac{1}{10}-2\cdot\left(\dfrac{1}{2}t-\dfrac{1}{10}\right)=2\left(t-\dfrac{5}{2}\right)-\dfrac{7}{10}\)

\(\Leftrightarrow\dfrac{1}{10}-t+\dfrac{1}{5}=2t-5-\dfrac{7}{10}\)

\(\Leftrightarrow-t-2t=-\dfrac{57}{10}-\dfrac{3}{10}=-6\)

hay t=2

\(\left(3x+1\right)\left(x-3\right)=\left(3x+1\right)\left(2x-5\right)\)

\(\Leftrightarrow\left(3x+1\right)\left(x-3\right)-\left(3x+1\right)\left(2x-5\right)=0\)

\(\Leftrightarrow\left(3x+1\right)\left(x-3-2x+5\right)=0\)

\(\Leftrightarrow\left(3x+1\right)\left(2-x\right)=0\)

\(\Leftrightarrow\left[\begin{matrix}3x+1=0\\2-x=0\end{matrix}\right.\)

\(\Leftrightarrow\)\(\left[\begin{matrix}3x=-1\\x=2\end{matrix}\right.\)

\(\Leftrightarrow\left[\begin{matrix}x=-\frac{1}{3}\\x=2\end{matrix}\right.\)

Vậy tập nghiệm của pt là \(S=\left\{-\frac{1}{3};2\right\}\)

Có : \(\left(3x+1\right)\left(x-3\right)=\left(3x+1\right)\left(2x-5\right)\)

\(\Leftrightarrow\) \(\left(3x+1\right)\left(x-3\right)-\left(3x+1\right)\left(2x-5\right)=0\)

\(\Leftrightarrow\) \(\left(3x+1\right)\left(x-3-2x+5\right)=0\)

\(\Leftrightarrow\) \(\left(3x+1\right)\left(-x+2\right)=0\)

\(\Leftrightarrow\) \(\left[\begin{matrix}3x+1=0\\-x+2=0\end{matrix}\right.\) \(\Leftrightarrow\) \(\left[\begin{matrix}3x=-1\\-x=-2\end{matrix}\right.\) \(\Leftrightarrow\) \(\left[\begin{matrix}x=\frac{-1}{3}\\x=2\end{matrix}\right.\)

Vậy phương trình có tập nghiệm \(S=\left\{\frac{-1}{3};2\right\}\)

2:

a: =>x-1=0 hoặc 3x+1=0

=>x=1 hoặc x=-1/3

b: =>x-5=0 hoặc 7-x=0

=>x=5 hoặc x=7

c: =>\(\left[{}\begin{matrix}x-1=0\\x+5=0\\3x-8=0\end{matrix}\right.\Leftrightarrow x\in\left\{1;-5;\dfrac{8}{3}\right\}\)

d: =>x=0 hoặc x^2-1=0

=>\(x\in\left\{0;1;-1\right\}\)

Bạn tách ra từng câu thoi nhe .

a. \(3-4x\left(25-2x\right)-8x^2+x-300=0\)

\(\Leftrightarrow3-100x+8x^2-8x^2+x-300=0\)

\(\Leftrightarrow-297-99x=0\)

\(\Leftrightarrow x=3\)

Vậy \(n_0\) của PT là: x=3

b. \(\Leftrightarrow\frac{\left(2-6x\right)}{5}-2+\frac{3x}{10}=7-\frac{3x+3}{4}\)

\(\Leftrightarrow\frac{\left(4-12x\right)}{5}-\frac{20}{10}+\frac{3x}{10}=\frac{\left(28-3x-3\right)}{4}\)

\(\Leftrightarrow\frac{\left(-16-9x\right)}{10}=\frac{\left(25-3x\right)}{4}\)

\(\Leftrightarrow-64-36x=250-30x\)

\(\Leftrightarrow-6x=314\)

\(\Leftrightarrow x=-\frac{157}{3}\)

Vậy -\(n_0\) của PT là: \(x=\frac{-157}{3}\)

c. \(5x+\frac{2}{6}-8x-\frac{1}{3}=4x+\frac{2}{5}-5\)

\(\Leftrightarrow-3x=4x-\frac{23}{5}\)

\(\Leftrightarrow7x=\frac{23}{5}\)

\(\Leftrightarrow x=\frac{23}{35}\)

Vậy \(n_0\) của PT là: \(x=\frac{23}{35}\)

d. \(3x+\frac{2}{3}-3x+\frac{1}{6}=2x+\frac{5}{3}\)

\(\Leftrightarrow\frac{5}{6}=2x+\frac{5}{3}\)

\(\Leftrightarrow x=-\frac{5}{12}\)

Vậy \(n_0\) của Pt là: \(x=-\frac{5}{12}\)