bn chép sai đề rùi, làm tui chết mệt, tui mới giải cho bn yến linh ( ở trên) bn xem nhé

xin loi nha

e dap an cua cau nay la j vay:

x-2(x+3)=3x+54

Bn thông cảm.Bài này mn ko bt làm

\(\left(x+3\right)^3-x\left(3x+1\right)^2+\left(2x+1\right)\left(4x^2-2x+1\right)-3x^2=54\)

\(\Leftrightarrow x^3+9x^2+27x+27-x\left(9x^2+6x+1\right)+8x^3+1-3x^2=54\)

=>\(9x^3+6x^2+27x+28-9x^3-6x^2-x=54\)

=>26x+28=54

=>26x=26

=>x=26/26=1

a) \(\left(x+3\right)^2-x\left(3x+1\right)^2+\left(2x+1\right)\left(4x^2-2x+1\right)-2x^2=54\)

=> x² + 6x + 9 - x(9x² + 6x + 1) + (2x)³ + 1³ - 2x² = 54

=> x² + 6x + 9 - 9x³ - 6x² - x + 8x³ + 1 - 2x² = 54

=> (-9x³ + 8x³) + (x² - 6x² - 2x²) + (6x - x) + (9 + 1) = 54

=> -x³ - 7x² + 5x + 10 = 54

=> -(x³ + 7x² - 5x - 10) = 54

=> phương trình vô nghiệm

b) (x + 3)³  - (x - 3)(x² + 3x + 9) + 6(x + 1)² + 3x = -33

=> x³ + 9x² + 27x + 27 - (x³ - 3³) + 6(x² + 2x + 1) + 3x = -33

=> x³ + 9x² + 27x + 27 - x³ + 27 + 6x² + 12x + 6 + 3x = -33

=> (x³ - x³) + (9x² + 6x²) + (27x + 12x + 3x) + (27 + 27 + 6) = -33

=> 15x² + 42x +  60 = -33

=> 15x² + 42x + 60 + 33 = 0

=> 15x² + 42x + 93 = 0

=> 3(5x² + 14x + 31) = 0

=> 5x² + 14x + 31 = 0

=> không tìm được x

`@` `\text {Ans}`

`\downarrow`

`a)`

`3x(4x-1) - 2x(6x-3) = 30`

`=> 12x^2 - 3x - 12x^2 + 6x = 30`

`=> 3x = 30`

`=> x = 30 \div 3`

`=> x=10`

Vậy, `x=10`

`b)`

`2x(3-2x) + 2x(2x-1) = 15`

`=> 6x- 4x^2 + 4x^2 - 2x = 15`

`=> 4x = 15`

`=> x = 15/4`

Vậy, `x=15/4`

`c)`

`(5x-2)(4x-1) + (10x+3)(2x-1) = 1`

`=> 5x(4x-1) - 2(4x-1) + 10x(2x-1) + 3(2x-1)=1`

`=> 20x^2-5x - 8x + 2 + 20x^2 - 10x +6x - 3 =1`

`=> 40x^2 -17x - 1 = 1`

`d)`

`(x+2)(x+2)-(x-3)(x+1)=9`

`=> x^2 + 2x + 2x + 4 - x^2 - x + 3x + 3=9`

`=> 6x + 7 =9`

`=> 6x = 2`

`=> x=2/6 =1/3`

Vậy, `x=1/3`

`e)`

`(4x+1)(6x-3) = 7 + (3x-2)(8x+9)`

`=> 24x^2 - 12x + 6x - 3 = 7 + (3x-2)(8x+9)`

`=> 24x^2 - 12x + 6x - 3 = 7 + 24x^2 +11x - 18`

`=> 24x^2 - 6x - 3 = 24x^2 + 18x -11`

`=> 24x^2 - 6x - 3 - 24x^2 + 18x + 11 = 0`

`=> 12x +8 = 0`

`=> 12x = -8`

`=> x= -8/12 = -2/3`

Vậy, `x=-2/3`

`g)`

`(10x+2)(4x- 1)- (8x -3)(5x+2) =14`

`=> 40x^2 - 10x + 8x - 2 - 40x^2 - 16x + 15x + 6 = 14`

`=> -3x + 4 =14`

`=> -3x = 10`

`=> x= - 10/3`

Vậy, `x=-10/3`

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