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Đáp án `+` Giải thích các bước giải:

`1)` `5x(1/5x-2)+3(6-1/3x^2) = 12`

`<=> x^2-10x+18-x^2 = 12`

`<=> (x^2-x^2)-10x+18 = 12`

`<=> -10x = -6`

`<=> x = 6/10`

`<=> x = 3/5`

Vậy `x=3/5`

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

`<=> 4x^2+3x-4x^2+8x = 10`

`<=> (4x^2-4x^2)+(3x+8x) = 10`

`<=> 11x = 10`

`<=> x = 10/11`

Vậy `x=10/11`

`3)` `5(x^2-3x+1)+x(1-5x) = x-2`

`<=> 5x^2-15x+5+x-5x^2-x+2 = 0`

`<=> (5x^2-5x^2)+(-15x+x-x)+(5+2) = 0`

`<=> -15x+7 = 0`

`<=> -15x = -7`

`<=> x = 7/15`

Vậy `x=7/15`

`4)` `12x^2-4x(3x-5) = 10x-17`

`<=> 12x^2-12x^2+20x-10x = -17`

`<=> (12x^2-12x^2)+(20x-10x) = -17`

`<=> 10x = -17`

`<=> x = -17/10`

Vậy `x=-17/10`

`5)` `4x(x-5)-7x(x-4)+3x^2 = 12`

`<=> 4x^2-20x-7x^2+28x+3x^2 = 12`

`<=> (4x^2-7x^2+3x^2)+(-20x+28x) = 12`

`<=> 8x = 12`

`<=> x = 12/8`

`<=> x = 3/2`

Vậy `x=3/2`

`6)` `4x^2-2x+3-4x(x-5) = 7x-3`

`<=> 4x^2-2x+3-4x^2+20x-7x = -3`

`<=> (4x^2-4x^2)+(-2x+20x-7x)+3 = -3`

`<=> 11x = -6`

`<=> x = -6/11`

Vậy `x=-6/11`

`7)` `-3x(x-5)+5(x-1)+3x^2 = 4-x`

`<=> -3x^2+15x+5x-5+3x^2+x = 4`

`<=> (-3x^2+3x^2)+(15x+5x+x)-5 = 4`

`<=> 21x = 9`

`<=> x = 9/21`

`<=> x = 3/7`

Vậy `x=3/7`

`8)` `7x(x-2)-5(x-1) = 21x^2-14x^2+3`

`<=> 7x^2-14x-5x+5 = 7x^2+3`

`<=> 7x^2-19x+5-7x^2 = 3`

`<=> (7x^2-7x^2)-19x = -2`

`<=> -19x = -2`

`<=> x = 2/19`

Vậy `x=2/19`

`9)` `3(5x-1)-x(x-2)+x^2-13x = 7`

`<=> 15x-3-x^2+2x+x^2-13x = 7`

`<=> (-x^2+x^2)+(15x+2x-13x)-3 = 7`

`<=> 4x = 10`

`<=> x = 10/4`

`<=> x = 5/2`

Vậy `x=5/2`

`10)` `1/5x(10x-15)-2x(x-5) = 12`

`<=> 2x^2-3x-2x^2+10x = 12`

`<=> (2x^2-2x^2)+(-3x+10x) = 12`

`<=> 7x = 12`

`<=> x = 12/7`

Vậy `x=12/7`