`( 19 . x + 2 . 5^2 ) : 14 = ( 13 - 8 )^2 - 4^2`
`⇔ ( 19 . x + 2 . 25 ) : 14 = 5^2 - 16`
`⇔ ( 19 . x + 50 ) : 14 = 25 - 16`
`⇔ ( 19 . x + 50 ) : 14 = 9`
`⇔ 19 . x + 50 = 9 xx 14`
`⇔ 19 . x + 50 = 126`
`⇔ 19 . x = 126 - 50`
`⇔ 19 . x = 76`
`⇔ x = 76 : 19`
`⇔ x = 4`
Vậy `, x = 4 .`