Đáp án:
`1, x = (-131)/130`
`2, x=7/2`
Giải thích các bước giải:
`1,`
`x + 30% x = -1,31`
`⇔ x × 1 + 3/10×x = (-131)/100`
`⇔ (1 + 3/10) x = (-131)/100`
`⇔ (10/10 + 3/10)x = (-131)/100`
`⇔ 13/10x = (-131)/100`
`⇔x=(-131)/100 ÷ 13/10`
`⇔ x = (-131)/100 × 10/13`
`⇔x= (-131)/130`
Vậy `x= (-131)/130`
`2,`
`(x-1/2) ÷ 1/3 + 5/7 = 9 5/7`
`⇔ (x - 1/2) ÷ 1/3 = 9 5/7 - 5/7`
`⇔ (x-1/2) ÷ 1/3 = 9`
`⇔ x - 1/2 = 9 × 1/3`
`⇔ x - 1/2 = 3`
`⇔ x =3+1/2`
`⇔x=6/2+1/2`
`⇔x=7/2`
Vậy `x=7/2`
