`16x^2-(4x-5)^2=15`
`⇔ 16x^2 - 16x^2 + 40x - 25 = 15`
`⇔ 40x = 15 + 25`
`⇔ 40x = 40`
`⇔ x = 1`
Vậy `S = {1}`
_________________________________
`(2x+3)^2-4(x-1)(x+1)=49`
`⇔ 4x^2 + 12x + 9 - 4x^2 + 4 = 49`
`⇔ (4x^2-4x^2) + 12x = 49 - 4 - 9`
`⇔ 12x = 36`
`⇔ x = 3`
Vậy `S = {3}`
_________________________________________
`(2x+1)(1-2x)+(1-2x)^2=18`
`⇔ 1 - 4x^2 + 1 - 4x + 4x^2 = 18`
`⇔ (4x^2-4x^2) - 4x = 18 - 1 - 1`
`⇔ -4x = 16`
`⇔ x = -4`
Vậy `S = {-4}`
__________________________________
`(3x-1)^2-(3x-2)^2=0`
`⇔ 9x^2 - 6x + 1 - 9x^2 + 12x - 4 = 0`
`⇔ (9x^2-9x^2) + 6x = 0 + 4 - 1`
`⇔ 6x = 3`
`⇔ x = 1/2`
Vậy `S = {1/2}`
