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18 tháng 10 2022

\(\left(3x-5\right)^3=2^2\times2^4\\ =>\left(3x-5\right)^3=2^6\\ =>\left(3x-5\right)^3=4^3\\ =>3x-5=4\\ =>3x=4+5\\ =>3x=9\\ =>x=3\)

18 tháng 10 2022

bằng -125

1: \(=6x^2+2x-15x-5-x^2+6x-9+4x^2+20x+25-27x^3-27x^2-9x-1\)

=-27x^3-18x^2+4x+10

2: =4x^2-1-6x^2-9x+4x+6-x^3+3x^2-3x+1+8x^3+36x^2+54x+27

=7x^3+37x^2+46x+33

5:

\(=25x^2-1-x^3-27-4x^2-16x-16-9x^2+24x-16+\left(2x-5\right)^3\)

\(=8x^3-60x^2+150-125+12x^2-x^3+8x-60\)

=7x^3-48x^2+8x-35

2:

a: =>x^2+3x-4x-12-(x^2-5x+x-5)=8

=>x^2-x-12-x^2+4x+5=8

=>3x-7=8

=>3x=15

=>x=5

b: =>3x^2+3x-2x-2-3x^2-21x=13

=>-20x=15

=>x=-3/4

c: =>x^2-25-x^2-2x=9

=>-2x=25+9=34

=>x=-17

d: =>x^3-1-x^3+3x=1

=>3x-1=1

=>3x=2

=>x=2/3

26 tháng 3 2020

a) (3x + 1)^2 - 2(3x + 1)(3x - 5) + (3x - 5)^2 

= 9x^2 + 6x + 1 - 18x^2 + 24x + 10 + 9x^2 - 30x + 25

= 36

b) (3x^2 - y)^2

= 9x^4 - 6x^2y + y^2

c) (3x + 5)^2 + (3x - 5)^2 - (3x + 2)(3x - 2)

= 9x^2 + 30x + 25 + 9x^2 - 30x + 25 - 9x^2 + 4

= 9x^2 + 54

d) 2x(2x - 1)^2 - 3x(x + 3)(x - 3) - 4x(x + 1)^2

= 8x^3 - 8x^2 + 2x - 3x^2 + 27x - 4x^3 - 8x^2 - 4x

= x^3 - 16x^2 + 25x

e) (x - 2)(x^2 + 2x + 4) - (x + 1)^2 + 3(x - 1)(x + 1)

= x^3 - 8 - x^2 - 2x - 1 + 3x^2 - 2

= x^3 + 2x^2 - 2x - 12

f) (x^4 - 5x^2 + 25)(x^2 + 5) - (2 + x^2)^2 + 3(1 + x^2)^2

= x^6 + 125 - 4 - 4x^2 - x^2 + 3 + 6x^2 + 3x^4

= x^6 + 2x^4 + 2x^2 + 124

28 tháng 7 2021

có sai đecc ko bạn.......gianroi

8 tháng 9 2021

\(a,3\left(2x-3\right)+2\left(2-x\right)=-3\\ \Leftrightarrow6x-9+4-2x=-3\\ \Leftrightarrow4x=2\\ \Leftrightarrow x=\dfrac{1}{2}\\ b,x\left(5-2x\right)+2x\left(x-1\right)=13\\ \Leftrightarrow5x-2x^2+2x^2-2x=13\\ \Leftrightarrow3x=13\\ \Leftrightarrow x=\dfrac{13}{3}\\ c,5x\left(x-1\right)-\left(x+2\right)\left(5x-7\right)=6\\ \Leftrightarrow5x^2-5x-5x^2-3x+14=6\\ \Leftrightarrow-8x=-8\\ \Leftrightarrow x=1\\ d,3x\left(2x+3\right)-\left(2x+5\right)\left(3x-2\right)=8\\ \Leftrightarrow6x^2+9x-6x^2-11x+10=8\\ \Leftrightarrow-2x=-2\\ \Leftrightarrow x=1\)

\(e,2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\\ \Leftrightarrow10x-16-12x+15=12x-16+11\\ \Leftrightarrow-14x=-4\\ \Leftrightarrow x=\dfrac{2}{7}\\ f,2x\left(6x-2x^2\right)+3x^2\left(x-4\right)=8\\ \Leftrightarrow12x^2-4x^3+3x^3-12x^2=8\\ \Leftrightarrow-x^3-8=0\\ \Leftrightarrow-\left(x^3+8\right)=0\\ \Leftrightarrow-\left(x+2\right)\left(x^2-2x+4\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-2\\x\in\varnothing\left(x^2-2x+4=\left(x-1\right)^2+3>0\right)\end{matrix}\right.\)

Bài 4:

a: Ta có: \(3\left(2x-3\right)-2\left(x-2\right)=-3\)

\(\Leftrightarrow6x-9-2x+4=-3\)

\(\Leftrightarrow4x=2\)

hay \(x=\dfrac{1}{2}\)

b: Ta có: \(x\left(5-2x\right)+2x\left(x-1\right)=13\)

\(\Leftrightarrow5x-2x^2+2x^2-2x=13\)

\(\Leftrightarrow3x=13\)

hay \(x=\dfrac{13}{3}\)

c: Ta có: \(5x\left(x-1\right)-\left(x+2\right)\left(5x-7\right)=6\)

\(\Leftrightarrow5x^2-5x-5x^2+7x-10x+14=6\)

\(\Leftrightarrow-8x=-8\)

hay x=1

17 tháng 10 2023

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a: \(\Leftrightarrow4x^2-20x+25-4x^2+9=5\)

=>-20x+34=5

=>-20x=-29

hay x=29/20

b: \(\Leftrightarrow x^3+9x^2+27x+27-x\left(x^2-16\right)=27\)

\(\Leftrightarrow x^3+9x^2+27x+27-x^3+16x-27=0\)

\(\Leftrightarrow9x^2+43x=0\)

=>x(9x+43)=0

=>x=0 hoặc x=-43/9

c: \(\Leftrightarrow9x^2-12x+4-9x^2-30x-25=4\)

=>-42x-21=4

=>-42x=25

hay x=-25/42

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

=>(4x+2)(2x+8)=0

=>x=-1/2 hoặc x=-4

18 tháng 9 2018

a) \(3\left(x^2-2x+1\right)+x\left(2-3x\right)=7\)

\(\Rightarrow3x^2-6x+3+2x-3x^2=7\)

\(\Rightarrow-4x+3=7\)

\(\Rightarrow-4x+3-7=0\)

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

\(\Rightarrow-4\left(x+1\right)=0\)

\(\Rightarrow x+1=0\)

\(\Rightarrow x=-1\)

b) \(5\left(x-2\right)+2\left(x+3\right)=10\)

\(\Rightarrow5x-10+2x+6=10\)

\(\Rightarrow7x-4=10\)

\(\Rightarrow7x=10+4=14\)

\(\Rightarrow x=\dfrac{14}{7}=2\)

c) \(\left(x+1\right)\left(-3\right)+5\left(x-4\right)=-3\)

\(\Rightarrow-3x-3+5x-20=-3\)

\(\Rightarrow2x-23=-3\)

\(\Rightarrow2x=-3+23=20\)

\(\Rightarrow x=\dfrac{20}{2}=10\)

d) \(2\left(x-1\right)-x\left(3-x\right)=x^2\)

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

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

\(\Rightarrow-x-2=0\)

\(\Rightarrow-x=2\)

\(\Rightarrow x=-2\)

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

\(\Rightarrow3x^2+15x-2x-10=3x^2\)

\(\Rightarrow3x^2-3x^2+13x-10=0\)

\(\Rightarrow13x-10=0\)

\(\Rightarrow13x=10\)

\(\Rightarrow x=\dfrac{10}{13}\)

e) \(4x\left(x+2\right)+x\left(4-x\right)=3x^2+12\)

\(\Rightarrow4x^2+8x+4x-x^2=3x^2+12\)

\(\Rightarrow3x^2+12x=3x^2+12\)

\(\Rightarrow3x^2+12x-3x^2-12=0\)

\(\Rightarrow12\left(x-1\right)=0\)

\(\Rightarrow x-1=0\)

\(\Rightarrow x=1\)

f) \(\dfrac{1}{3}x\left(3x+6\right)-x\left(x-5\right)=9\)

\(\Rightarrow x^2+2x-x^2+5x=9\)

\(\Rightarrow7x=9\)

\(\Rightarrow x=\dfrac{9}{7}\)