Question

giúp mình vs ạ

Answer 1

Lời giải:

a. $\frac{3}{4}>\frac{2}{4}$

$\Rightarrow \frac{3}{4}.(-1)< \frac{2}{4}.(-1)$

$\Rightarrow \frac{3}{-4}< \frac{2}{-4}$

b.

$\frac{-1}{2^2.3}$

$\frac{-12}{2^2.3^2.5}=\frac{-12}{2^2.3.15}$

Có:

$1> \frac{12}{15}$

$\Rightarrow 1.\frac{-1}{2^2.3}< \frac{12}{15}.\frac{-1}{2^2.3}$

$\Rightarrow \frac{-1}{2^2.3}< \frac{-12}{2^2.3.15}$

Hay $\frac{-1}{2^2.3}< \frac{-12}{2^2.3^2.5}$

c.

$\frac{-6}{15}=\frac{-2}{5}=\frac{-12}{30}$

$\frac{-5}{6}=\frac{-25}{30}$

Có: $\frac{12}{30}< \frac{25}{30}\Rightarrow \frac{-12}{30}> \frac{-25}{30}$

$\Rightarrow \frac{-6}{15}> \frac{-5}{6}$
d.

$\frac{5}{-21}=\frac{-50}{210}$

$\frac{-7}{30}=\frac{-49}{210}$

Có: $\frac{50}{210}> \frac{49}{210}$

$\Rightarrow \frac{-50}{210}< \frac{-49}{210}$

$\Rightarrow \frac{5}{-21}< \frac{-7}{30}$