Question

Giá trị tuyệt đối của một số hữu tỉ
a ) \(3-\left|\dfrac{-1}{2}\right|\)
b ) \(\left|\dfrac{-1}{4}\right|+\dfrac{3}{4}-|-1|\)
c )\(\left|0,25\right|=-\left(-0,25\right)\)

Answer 1

a,

\(3-\left|\dfrac{-1}{2}\right|\\ =3-\dfrac{1}{2}\\ =\dfrac{6}{2}-\dfrac{1}{2}\\ =\dfrac{5}{2}\)

b,

\(\left|\dfrac{-1}{4}\right|+\dfrac{3}{4}-\left|-1\right|\\ =\dfrac{1}{4}+\dfrac{3}{4}-1\\ =1-1\\ =0\)

c,

\(\left|0,25\right|=-\left(-0,25\right)\\ 0,25=0,25\)

Answer 2

a ) $3-\left|\frac{-1}{2}\right|$

= 3 - \(\dfrac{1}{2}\)

= \(\dfrac{6}{2}\)- \(\dfrac{1}{2}\)= \(\dfrac{5}{2}\).

b ) $\left|\frac{-1}{4}\right|+\frac{3}{4}-|-1|$

= \(\dfrac{1}{4}\)+ \(\dfrac{3}{4}\) - 1.

= 1 - 1= 0.

c )$\left|0,25\right|=-\left(-0,25\right)$

=> 0,25 = 0,25.

Answer 3

a) \(3-\left|\dfrac{-1}{2}\right|\)

\(=3-\dfrac{1}{2}\)

\(=\dfrac{6}{2}-\dfrac{1}{2}\)

\(=\dfrac{5}{2}\)

b) \(\left|\dfrac{-1}{4}\right|+\dfrac{3}{4}-\left|-1\right|\)

\(=\dfrac{1}{4}+\dfrac{3}{4}-1\)

\(=1-1=0\)

c) Ta có: \(\left|0.25\right|=0.25\)

Áp dụng quy tắc dấu ngoặc ta có: \(0.25=-\left(-0.25\right)\\ \Rightarrow\left|0.25\right|=-\left(-0.25\right)\\ \rightarrowđpcm\)