`c, ( x + 3/5 )^2 + 1 16/25 = 9% : 4,5%`
`⇔ ( x + 3/5 )^2 + 41/25 = 9/100 : 45/1000`
`⇔ ( x + 3/5 )^2 + 41/25 = 2`
`⇔ ( x + 3/5 )^2 = 2 - 41/25`
`⇔ ( x + 3/5 )^2 = 9/25`
Trường hợp 1 :
`( x + 3/5 )^2 = ( 3/5 )^2`
`⇔ x + 3/5 = 3/5`
`⇔ x = 3/5 - 3/5`
`⇔ x = 0`
Trường hợp 2 :
`( x + 3/5 )^2 = ( ( - 3 )/5 )^2`
`⇔ x + 3/5 = ( - 3 )/5`
`⇔ x = ( - 3 )/5 - 3/5`
`⇔ x = ( - 6 )/5`
Vậy , `x ∈ { 0 ; ( - 6 )/5 }`
