b. 6x(x - 5) - x(6x + 3)

= x(6x - 30) - x(6x + 3)

= x(6x - 30 - 6x - 3)

= x(-33)

= -33x

\(1,\\ a,=-35x^5y^4z\\ b,=6x^2-30x-6x^2-3x=-33x\\ c,=x^3-9x^2-2x^2+18x-x+9=x^3-11x^2+17x+9\\ 2,\\ A\left(x\right)+B\left(x\right)=10-2x+4x^3-5x^2-10x^3-5x+6x^2-20\\ =-6x^3+x^2-7x-10\\ A\left(x\right)-B\left(x\right)=10-2x+4x^3-5x^2+10x^3+5x-6x^2+20\\ =14x^3-11x^2+3x+30\\ 3,\\ a,M\left(x\right)=5x+20=0\\ \Leftrightarrow x=-4\\ b,N\left(x\right)=100x^2-49=0\\ \Leftrightarrow\left(10x-7\right)\left(10x+7\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{10}\\x=-\dfrac{7}{10}\end{matrix}\right.\\ c,P\left(x\right)=3x-15=0\\ \Leftrightarrow x=5\)

Bài 1;

a)\(5x^3yz.\left(-7x^2y^3\right)=-35.x^5y^4z\)

b)\(6x\left(x-5\right)-x\left(6x+3\right)=6x^2-30x-6x^2-3x=-33x\)

c) \(\left(x-9\right)\left(x^2-2x-1\right)=x^3-2x^2-x-9x^2+18x+9=x^3-11x^2+17x+9\)

a) 6x + 15 = 75

6x = 75 - 15

6x = 60

x = 60 : 6

x = 10

b) x - 12 = (-27)

x = (-27) + 12

x = -15

c) 23 + (x - 5) : 4 = 3⁸ : 3⁵

23 + (x - 5) : 4 = 3³

23 + (x - 5) : 4 = 27

23 + (x - 5) = 27 x 4

23 + (x - 5) = 108

x - 5 = 108 - 23

x - 5 = 85

x = 85 + 5

x = 90

\(\Leftrightarrow5^{x+5}=24+1=25\)

=>x+5=2

hay x=-3

5\(^{x+5}\)-1=8.3

5\(^{x+5}\)-1=24

5\(^{x+5}\)=25

5\(^{x+5}\)=5\(^2\)

=>x+5=2

=>x=-3

vậy x=-3

5^x+5-1=24
5^x+5   =24+1
5^x+5   =25
5^x+5   =5²
x+5    =2
x        =2-5
x        =-3

Đề thiếu rồi bạn ơi

a, ( 8x - 3 ) ( 3x + 2 ) - ( 4x + 7 ) ( x + 4 ) = ( 2x + 1 ) ( 5x - 1 )

 ( 24x² + 16x - 9x - 6 ) - ( 4x² - 16x - 7x + 28 ) = 10x² - 2x + 5x -1

24x² + 16x - 9x - 6 -4x² - 16x - 7x - 10x² + 2x - 5x = 6 + 28 - 1

10x² -19x = 33

10x² - 19x -33 = 0 \(\Leftrightarrow\)10x( x+ 3 ) + 11 ( x- 3 ) = 0

=>  ( x- 3 ) ( 10x + 11 ) = 0\(\Rightarrow\orbr{\begin{cases}x=3\\x=\frac{-11}{10}\end{cases}}\)

b, 4( x - 1 ) ( x + 5 ) - ( x + 2 ) ( x + 5 ) = 3( x - 1 ) ( x + 2 )

4( x² - 5x - x + 5 ) - ( x² + 5x + 2x + 10 ) = 3( x² + 2x - x - 2 )

4x² - 20x - 4x + 20 - x² - 5x - 2x - 10 = 3x² + 6x - 3x - 6

( 4x² - x² ) + ( -20x - 4x - 5x - 2x ) + 20 - 10 = 3x² + ( 6x - 3x ) - 6

3x² - 31x - 3x² - 3x = -6-10

-34x = -16

x = \(\frac{8}{17}\)

\(5^2-\left(5x-3\right)=43\)

\(\Leftrightarrow25-5x+3=43\)

\(\Leftrightarrow5x=-15\)

\(\Leftrightarrow x=-3\)

5² - (5x-3) = 43 

=> 5² - 5x +3 = 43 

=> 5.5-5x = 43 -3 

=> 5.(5-x) = 40 

=> 5-x = 8 

=> x = 5-8 

=> x =( -3 )

Vậy x = (-3)

\(5^2\)\(-\left(5x-3\right)=43\)

⇒ 25 - 5x + 3 = 43

⇒ 28 - 5x = 43

⇒ 5x = -15

⇒ x = -3 

Vậy x= -3

a ) 14,9 + x = 58,3

     x = 58,3 - 14,9

       x = 43,4

b ) 75 : 5 + x = 100

     25 + x =100

      x = 100 - 25 

      x = 75

a. 14,9 + x = 58,3

              x = 58,3 - 14,9

              x = 43,4

b. 75 : 5 + x = 100

          15 + x = 100

                 x = 100 - 15

                 x = 85

Sorry mình nhầm câu b 

75 : 5 + x = 100

15 + x =100

x = 100 - 15

x =85