1.Tìm x:

a) -13(x-1)+3(2-x)=6

-13x-x+6-3x=6

x-x-3x=6+13-6

5x=13

  x=13/5

vậy x=13/5

b)7.(x-3)-3(3-x)=0

7x-21-9-3x=0

7x-3x=0+21+9

4x=30

  x=15/2

vậy x=15/2

c)2|3x-1|-5=7

2|3x-1|=7+5

2|3x-1|=12

|3x-1|=12:2

|3x-1|=6

* 3x-1=6             * 3x-1=-6

   3x=6+1              3x=-6+1

   3x=7                   3x=-5 

     x=7/3                 x=-5/3

vậy x=7/3 hoặc x=-5/3

Bài làm :

\(a,\left(8-5x\right)\left(x+2\right)+4\left(x-2\right)\left(x+1\right)+2\left(x-2\right)\left(x+2\right)+10\)

\(=8x+16-5x^2-10x+\left(4x-8\right)\left(x+1\right)+2\left(x^2-2^2\right)+10\)

\(=8x+16-5x^2-10x+4x^2+4x-8x-8+2x^2-8+10\)

\(=\left(8x-10x+4x-8x\right)+\left(-5x^2+4x^2+2x^2\right)+\left(16-8-8+10\right)\)

\(=-6x+x^2+10\)

a)\(\left(8-5x\right)\left(x+2\right)+4\left(x-2\right)\left(x+1\right)+2\left(x-2\right)\left(x+2\right)+10\)\(=8x+16-5x^2-2+4x-8x-8+2x-4x-4+10\)\(=\left(8x+4x-8x+2x-4x\right)+\left(16-2-8-4+10\right)+5x^2\)

\(=2x+12+5x^2\)

b)\(4\left(x-1\right)\left(x+5\right)-\left(x+2\right)\left(x+5\right)-3\left(x-1\right)\left(x+2\right)\)

\(=4x-4x-20-\left[x^2+5x+2x+10\right]-3\left[x^2+2x-1x-2\right]\)

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

\(=\left(4x-4x-5x-2x-6x+3x\right)+\left(-20-10+6\right)+\left(-x^2-3x^2\right)\)

\(=-10x-24-4x^2\)

c)\(\left(x^{2n}+x^ny^n+y^{2n}\right)\left(x^n-y^n\right)\left(x^{3n}+y^{3n}\right)\)

Xét tích \(\left(x^{2n}+x^ny^n+y^{2n}\right)\left(x^n-y^n\right)\Leftrightarrow\left(x^n\right)^3-\left(y^n\right)^3=x^{3n}-y^{3n}\)

Thay vào bt đã cho ta có \(\left(x^{3n}-y^{3n}\right)\left(x^{3n}+y^{3n}\right)\)

\(\Leftrightarrow\left(x^{3n}\right)^2-\left(y^{3n}\right)^2=x^{6n}-y^{6n}\)

a) ( 8 - 5x )( x + 2 ) + 4( x - 2 )( x + 1 ) + 2( x - 2 )( x + 2 ) + 10

= -2x - 5x² + 16 + 4( x² - x - 2 ) + 2( x² - 4 ) + 10

= -2x - 5x² + 16 + 4x² - 4x - 8 + 2x² - 8 + 10

= x² - 6x + 10

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

= 4( x² + 4x - 5 ) - ( x² + 7x + 10 ) - 3( x² + x - 2 )

= 4x² + 16x - 20 - x² - 7x - 10 - 3x² - 3x + 6

= 6x - 24 = 6( x - 4 )

c) ( x²ⁿ + xⁿyⁿ + y²ⁿ )( xⁿ - yⁿ )( x³ⁿ + y³ⁿ )

= [ ( xⁿ )³ - ( yⁿ )³ ]( x³ⁿ + y³ⁿ )

= ( x³ⁿ - y³ⁿ )( x³ⁿ + y³ⁿ )

= ( x³ⁿ )² - ( y³ⁿ )² = x⁶ⁿ - y⁶ⁿ

Mk lm câu b bài 2 há!

b, ( 8x - 3 )( 3x + 2 ) - ( 4x + 7 )( x + 4 ) = ( 2x +1 )( 5x - 1) =- 33

Pt <=> 3x ( 8x - 3 ) + 2( 8x- 33) - ( x ( 4x + 7) ) + ( 2x + 1) - 5x ( 2x + 1) + 33 = 0

<=> 24x² - 9x + 16x - 6 - ( 4x² + 7x + 16x + 28) + 2x + 1 - 10x² - 5x + 33 = 0

<=> 24x² - 9x + 16x - 6 - 4x² - 7x - 16x - 28 + 2x + 1 - 10x² - 19x = 0 <=> x ( 10x - 19) = 0 

=> \(\orbr{\begin{cases}x=0\\10x-19=0\end{cases}}\) \(\Rightarrow\orbr{\begin{cases}x=0\\x=\frac{19}{10}\end{cases}}\) 

^^ Ok con tê tê!

a: \(4x^2\left(3x^{n+1}-2x^n\right)\)

\(=4x^2\cdot3x^{n+1}-4x^2\cdot2x^n\)

\(=12x^{n+3}-8x^{n+2}\)

b: \(2\left(x^{2n}+2x^ny^n+y^{2n}\right)-y^n\left(4x^n+2y^n\right)\)

\(=2x^{2n}+4x^ny^n+2y^{2n}-4x^ny^n-2y^{2n}\)

\(=2x^{2n}\)

c: \(=\left(x^{3n}-y^{3n}\right)\left(x^{3n}+y^{3n}\right)\)

\(=x^{6n}-y^{6n}\)

d: \(=4^n\cdot4-3\cdot4^n=4^n\)

a: 4x2(3xn+1−2xn)4x2(3xn+1−2xn)

=4x2⋅3xn+1−4x2⋅2xn=4x2⋅3xn+1−4x2⋅2xn

=12xn+3−8xn+2=12xn+3−8xn+2

b: 2(x2n+2xnyn+y2n)−yn(4xn+2yn)2(x2n+2xnyn+y2n)−yn(4xn+2yn)

=2x2n+4xnyn+2y2n−4xnyn−2y2n=2x2n+4xnyn+2y2n−4xnyn−2y2n

=2x2n=2x2n

c: =(x3n−y3n)(x3n+y3n)=(x3n−y3n)(x3n+y3n)

=x6n−y6n=x6n−y6n

d: