Question

Câu 13. (1,5 điểm) Thực hiện các phép tính:

a) \(\frac{-1}{5} + \frac{-9}{5}\)

b) \(\sqrt{25} + \sqrt{1,21} - \frac{2}{3} \cdot \sqrt{\frac{36}{4}}\)

Câu 14: (2 điểm) Tìm x biết

a) \(x + \frac{2}{5} = \frac{7}{10}\)

b) \(\frac{x}{-26} = -\frac{7}{2}\)

c) \(|x - \frac{1}{2}| = \frac{5}{6}\)

Answer 1

Câu `14`

`a, x + 2/5 = 7/10`

`x = 7/10 - 2/5`

`x = 7/10 - 4/10`

`x = 3/10`

`b, x/(-26) = 7/2`

`2x = 7 . (-26)`

`2x = -182`

`x= -182 : 2`

`x = -91`

`c, |x-1/2|-1/3=5/6`

`|x-1/2|=5/6+1/3`

`|x-1/2|=5/6+2/6`

`|x-1/2| = 7/6`

`x-1/2=+-7/6`

`[(x-1/2=7/6),(x-1/2=-7/6):}`

`[(x = 7/6 + 1/2),(x=-7/6+1/2):}`

`[(x=7/6+3/6),(x=-7/6+3/6):}`

`[(x = 5/3),(x = -2/3):}`

Answer 2

`a, (-1)/5 + (-9)/5 = (-1 + (-9))/5 = (-10)/5 = -2`

`b, \sqrt(25) + sqrt(1,21) - 2/3 . sqrt(36/4)`

`= 5 + 1,1 - 2/3 . 6/2`

`= 6,1 - 2`

`= 4,1`