`d, 5(x - y) - y(x - y)`
`= (x - y) . (5 - y)`
`e, y(x - z) + 7(z - x)`
`= y(x - z) - 7(x - z)`
`= (x - z) . (y - 7)`
`f, 27x^2(y - 1) - 9x^3(1 - y)`
`= 27x^2(y - 1) + 9x^3(y - 1)`
`= (y - 1) . (27x^2 + 9x^3)`
`= (y - 1) . 9x^2(3 + x)`
Bài 36:
`a, 5(x + 3) - 2x(3 + x) = 0`
`(x + 3) . (5 - 2x) = 0`
`=> [(x + 3 = 0 ),(5 - 2x = 0):}`
`=> [(x = -3),(2x = 5 => x = 5/2):}`
Vậy `x ∈ {-3;5/2}`
`b, 4x(x - 2004) - x + 2004 = 0`
`4x(x - 2004) - (x - 2004) = 0`
`(x - 2004) . (4x - 1) = 0`
`=> [(x - 2004 = 0),(4x - 1 = 0):}`
`=> [(x = 2004),(4x = 1 => x = 1/4):}`
Vậy `x ∈ {2004;1/4}`
`c, (x + 1)^2 = x + 1`
`(x + 1)^2 - (x + 1) = 0`
`(x + 1) . (x + 1 - 1) = 0`
`=> [(x + 1 = 0),(x + 1 - 1 = 0):}`
`=> [(x = -1),(x = 0):}`
Vậy `x ∈ {-1;0}`
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