Đáp án + Giải thích các bước giải:
a, `3(x-2)^2-3x(x+1) = -2`
`=> 3x^2 - 12x + 12 - 3x^2 - 3x = -2`
`=> (3x^2-3x^2)-(12+3x) = -2 - 12`
`=> -15x = -14`
`=> x = 14/15`
Vậy `x \in {14/15}`
b, `5(x-1)(x+1)-(2x+1)^2=x^2+5x-3`
`=> 5x^2-5-4x^2-4x-1=x^2+5x-3`
`=> x^2 - 4x - 6 = x^2 + 5x - 3`
`=> x^2 - 4x - 6 - x^2 - 5x + 3 = 0`
`=> (x^2-x^2) - (4x+5x) = 0 - 3`
`=> -9x = -3`
`=> x = 1/3`
Vậy `x \in {1/3}`
c, `(3x-2)(3x+2)-9(x-1)^2=-2x-4`
`=> 9x^2 - 4 - 9x^2 + 18x -9 = -2x -4`
`=> (9x^2-9x^2) + 18x - (9+4) = -2x - 4`
`=> 18x - 13 = -2x - 4`
`=> 18x + 2x = 13 -4`
`=> 20x = 9`
`=> x = 9/20`
Vậy `x \in {9/20}`
d, `(5x+1)^2+(2-5x)(5x+2)=4x-3`
`=> 25x^2 + 10x + 1 + 4 - 25x^2 = 4x - 3`
`=> (25x^2-25x^2) + 10x + (4+1) = 4x - 3`
`=> 10x + 5 = 4x - 3`
`=> 10x - 4x = -3-5`
`=> 6x = -8`
`=> x = -4/3`
Vậy `x \in {-4/3}`
