Đáp án+Giải thích các bước giải:
`23.`
`3x^2 - 3x(x-2) = 36`
`<=> 3x^2 - 3x^2 + 6x = 36`
`<=> 6x = 36`
`<=> x = 6`
Vậy `x = 6`
`24.`
`6x(x-4)+2x(2-3x) = -25`
`<=> 6x^2 - 24x + 4x - 6x^2 = -25`
`<=> (6x^2 - 6x^2)-(24x - 4x) = -25`
`<=> -20x = -25`
`<=> x = 5/4`
Vậy `x = 5/4`
`25.`
`5x^2(3x-2) - 3x^2(5x+2) + 2x(3+8x) = 21`
`<=> 15x^3 - 10x^2 - 15x^3 - 6x^2 + 6x + 16x^2 = 21`
`<=> (15x^3 - 15x^3)-(10x^2 + 6x^2 - 16x^2) + 6x = 21`
`<=> 6x = 21`
`<=> x = 7/2`
Vậy `x = 7/2`
`26.`
`5x(4x^2 - 2x + 1)-2x(10x^2 - 5x - 2) = -36`
`<=> 20x^3 - 10x^2 + 5x - 20x^3 + 10x^2 + 4x = -36`
`<=> (20x^3 - 20x^3)-(10x^2 - 10x^2)+(5x+4x) = -36`
`<=> 9x = -36`
`<=> x= -4`
Vậy `x = -4`
