\(\dfrac{25.9-25.17}{-8.80-8.10}=\dfrac{-200}{-720}=\dfrac{5}{18}\)

\(\dfrac{48.12-48.15}{-3.270-3.30}=\dfrac{-144}{-900}=\dfrac{4}{25}\)

a, Quy đồng

\(\dfrac{5}{18}=\dfrac{5\times25}{18\times25}=\dfrac{125}{450}\)

\(\dfrac{4}{25}=\dfrac{4.18}{25.18}=\dfrac{72}{450}\)

25.9-25.17/-8.80-.10=25.(9-17)/-8(80+10)=25.(-8)/-8.90=25/90=5/18

48.12-48.15/-3.270-3.30=48.(12-15)/-3(270+30)=48.-3/-3.300=48/300=4/25

thông cảm e mới học lớp 6 nên sai thì thôi còn chỗ -3 hay -8 là vì thay -2 lần trừ  ra cộng

 ((25.9 - 25.17))(( - 8.80 - 8.10)) ) và  ((48.12 - 48.15))(( - 3.270 - 3.30)) ). hãy so sánh 2 phân số trên

lấy máy tính ra bấm là nó ra liền à

\(\frac{-35}{280}=\frac{\left(-35\right):35}{280:35}=\frac{-1}{8}\)     

\(\frac{24}{72}=\frac{24:24}{72:24}=\frac{1}{3}\)

\(\frac{15}{-105}=\frac{-15}{105}=\frac{\left(-15\right):15}{105:15}=\frac{-1}{7}\)

\(\frac{36}{240}=\frac{36:12}{240:12}=\frac{3}{20}\)

\(\frac{125}{1000}=\frac{125:125}{1000:125}=\frac{1}{8}\)

\(\frac{198}{126}=\frac{198:18}{126:18}=\frac{11}{7}\)

Câu a:

\(\frac{3939-101}{3.2929+505}\)

= \(\frac{101.\left(39-1\right)}{101.\left(3.29+5\right)}\)

= \(\frac{38}{87+5}\)

= \(\frac{38}{92}\)

= \(\frac{19}{46}\)

Câu c:

\(\frac{6.9-2.17}{63.3-119}\)

= \(\frac{2.\left(3.9-17\right)}{7.\left(9.3-17\right)}\)

= \(\frac27\)

Câu 1:

A = \(\frac{25.9-25.17}{-8.80-8.10}\)

A = \(\frac{25.\left(9-17\right)}{-8.10\left(8+1\right)}\)

A = \(\frac{5.5.\left(-8\right)}{-8.10.9}\)

A = \(\frac{5.5.2.4}{2.4.5.2.9}\)

A = \(\frac{5}{18}\)

B = \(\frac{48.12-48.15}{-3.270-3.30}\)

B = \(\frac{48.\left(12-15\right)}{-3.30\left(9+1\right)}\)

B = \(\frac{6.8.\left(-3\right)}{-3.30.10}\)

B = \(\frac{6.2.4.\left(-3\right)}{-3.5.6.2.5}\)

B = \(\frac{4}{25}\) = \(\frac{20}{125}\) < \(\frac{20}{72}\) = \(\frac{5}{18}\)

A > B

Câu 2:

A = \(\frac{2^5.7+2^5}{2^5-2^5.3}\)

A = \(\frac{2^5.\left(7+1\right)}{2^5-2^5.3}\)

A = \(\frac{2^5.8}{2^5.\left(1-3\right)}\)

A = \(\frac{8}{-2}\)

A = -4

B = \(\frac{3^4.5-3^6}{3^4.13+3^4}\)

B = \(\frac{3^4.\left(1-3^2\right)}{3^4.\left(13+1\right)}\)

B = \(\frac{1-9}{14}\)

B = \(\frac{-8}{14}\)

B = \(\frac{-4}{7}\) > - 4

Vậy A < B

\(\frac{25.9-25.17}{-8.80-8.10}=\frac{25\left(9-17\right)}{-8\left(80+10\right)}=\frac{25.\left(-8\right)}{\left(-8\right).90}=\frac{25}{90}=\frac{5}{18}\)

dễ thôi

\(\dfrac{25.9-25.17}{-8.80-8.10}=\dfrac{25.\left(9-17\right)}{-8.\left(80+10\right)}=\dfrac{25.\left(-8\right)}{-8.90}=\dfrac{25}{90}=\dfrac{5}{18}\)

\(\dfrac{48.12-48.15}{-3.270-3.30}=\dfrac{48.\left(12-15\right)}{-3.\left(270+30\right)}=\dfrac{48.\left(-3\right)}{-3.300}=\dfrac{48}{300}=\dfrac{4}{25}\)

MC = 450

\(\dfrac{5}{18}=\dfrac{5.25}{18.25}=\dfrac{125}{450}\)

\(\dfrac{4}{25}=\dfrac{4.18}{25.18}=\dfrac{72}{450}\)

$\frac{25.9-25.17}{-8.80-8.10}=\frac{25.\left(9-17\right)}{-8.\left(80+10\right)}=\frac{25.\left(-8\right)}{-8.90}=\frac{25}{90}=\frac{5}{18}$

$\frac{48.12-48.15}{-3.270-3.30}=\frac{48.\left(12-15\right)}{-3.\left(270+30\right)}=\frac{48.\left(-3\right)}{-3.300}=\frac{48}{}$

Ta có :

\(\frac{25.9-15.17}{\left(-8\right).80-8.10}=\frac{5^2.3^2-3.5.17}{\left(-8\right).\left(80+10\right)}=\frac{3.5.\left(3.5-17\right)}{\left(-8\right).90}=\frac{15.\left(-2\right)}{\left(-8\right).90}=\frac{-30}{\left(-8\right).90}=\frac{1}{8.3}=\frac{1}{24}\)

\(-8 .80 - 8 . 10 \)

\(=\)\(-8 . ( 80 - 10 )\)

\(=\)\(-8 . 70\)

\(=\)\(-560\)