`(2x+3)^2 - (2x+1)(2x-1) = 22`
`⇔ 4x^2 + 12x + 9 - 4x^2 + 1 = 22`
`⇔ (4x^2-4x^2) + 12x = 22 - 1 - 9`
`⇔ 12x = 12`
`⇔ x = 1`
Vậy `S = {1}`
....................................................
`(2x-1)^2-2x(2x-3) = 5`
`⇔ 4x^2 - 4x + 1 - 4x^2 + 6x = 5`
`⇔ (4x^2-4x^2) + (6x-4x) = 5 - 1`
`⇔ 2x = 4`
`⇔ x = 2`
Vậy `S = {2}`
......................................................
`(x-3)^2 - 4 = 0`
`⇔ (x-3)^2 = 4`
`⇔ |x-3| = 2`
`1)` `x - 3 = 2 ⇔ x = 5`
`2)` `x - 3 = -2 ⇔ x = 1`
Vậy `S = {1,5}`
......................................................
`(2x-1)^2+(x+3)^2-5(x+7)(x-7) = 0`
`⇔ 4x^2 - 4x + 1 + x^2 + 6x + 9 - 5x^2 + 245 = 0`
`⇔ (5x^2-4x^2-x^2) + (6x-4x) = 0 - 245 - 9 - 1`
`⇔ 2x = -255`
`⇔ x = -255/2`
Vậy `S = {-255/2}`
..............................................................
`25x^2 - 9 = 0`
`⇔ 25x^2 = 9`
`⇔ x^2 = 9/25`
`⇔ |x| = 3/5`
`⇔ x = \pm3/5`
Vậy `S = {-3/5,3/5}`
..............................................................
`(x+4)^2-(x+1)(x-1)=16`
`⇔ x^2 + 8x + 16 - x^2 + 1= 16`
`⇔ (x^2-x^2) + 8x = 16 - 1 - 16`
`⇔ 8x = -1`
`⇔ x = -1/8`
Vậy `S = {-1/8}`
