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\(A=-\frac{9}{10^{2012}}+-\frac{19}{10^{2011}}=-\frac{9}{10^{2012}}+-\frac{9}{10^{2011}}+-\frac{10}{10^{2011}}\)
\(B=-\frac{9}{10^{2011}}+-\frac{19}{10^{2012}}=-\frac{9}{10^{2011}}+-\frac{9}{10^{2012}}+-\frac{10}{10^{2012}}\)
Mà \(-\frac{9}{10^{2012}}=-\frac{9}{10^{2012}};-\frac{9}{10^{2011}}=-\frac{9}{10^{2011}};-\frac{10}{10^{2012}}>-\frac{10}{10^{2011}}\)
\(\Rightarrow-\frac{9}{10^{2011}}+-\frac{9}{10^{2012}}+-\frac{10}{10^{2012}}>-\frac{9}{10^{2011}}+-\frac{9}{10^{2012}}+-\frac{10}{10^{2011}}\)
\(\Rightarrow B>A\)
Chúc bạn học tốt !!!!
1.
Ta có:
* 279
= ( 3.9)9
= 39.99
= 3.38.99
=3.(32)4.99
= 3.94.99
= 3.913
* 817
= (92)7
= 914
M = 817 - 279 - 913
= 914 + 3.913 – 913
=913(9 – 3 – 1)
= 5.912 chia hết cho 5 và 9 => chia hết cho45
Vậy M chia hết cho 45.
\(4x+7⋮x-1\)
\(\Rightarrow4x-4+11⋮x-1\)
\(\Rightarrow4\left(x-1\right)+11⋮x-1\)
\(4\left(x-1\right)⋮x-1\)
\(\Rightarrow11⋮x-1\)
\(\Rightarrow x-1\inƯ\left(11\right)=\left\{-1;1;-11;11\right\}\)
\(\Rightarrow x\in\left\{0;2;10;12\right\}\)
vậy_
\(x-5⋮x-6\)
\(\Rightarrow x-6+1⋮x-6\)
\(x-6⋮x-6\)
\(\Rightarrow1⋮x-6\)
\(\Rightarrow x-6\inƯ\left(1\right)=\left\{-1;1\right\}\)
\(\Rightarrow x\in\left\{5;7\right\}\)
vậy_
4x+7⋮x−1
⇒4x−4+11⋮x−1
⇒4(x−1)+11⋮x−1
4(x−1)⋮x−1
⇒11⋮x−1
⇒x−1∈Ư(11)={−1;1;−11;11}
⇒x∈{0;2;10;12}
vậy_
x−5⋮x−6
⇒x−6+1⋮x−6
x−6⋮x−6
⇒1⋮x−6
⇒x−6∈Ư(1)={−1;1}
⇒x∈{5;7}
vậy ....................
a: \(\dfrac{-7}{15}=\dfrac{-7\cdot4}{15\cdot4}=\dfrac{-28}{60}\)
\(\dfrac{5}{12}=\dfrac{5\cdot5}{12\cdot5}=\dfrac{25}{60}\)
b: \(\dfrac{1}{5}=\dfrac{1\cdot6}{5\cdot6}=\dfrac{6}{30}\)
\(\dfrac{-2}{3}=\dfrac{-2\cdot10}{3\cdot10}=\dfrac{-20}{30}\)
\(\dfrac{7}{10}=\dfrac{7\cdot3}{10\cdot3}=\dfrac{21}{30}\)
c: \(\dfrac{-15}{50}=\dfrac{-15\cdot3}{50\cdot3}=\dfrac{-45}{150}\)
\(\dfrac{9}{10}=\dfrac{9\cdot15}{10\cdot15}=\dfrac{135}{150}\)
\(\dfrac{26}{-30}=\dfrac{-26}{30}=\dfrac{-26\cdot5}{30\cdot5}=\dfrac{-130}{150}\)
d: \(\dfrac{7}{10}=\dfrac{7\cdot51}{10\cdot51}=\dfrac{357}{510}\)
\(\dfrac{-5}{-15}=\dfrac{1}{3}=\dfrac{1\cdot170}{3\cdot170}=\dfrac{170}{510}\)
\(\dfrac{3}{17}=\dfrac{3\cdot30}{17\cdot30}=\dfrac{90}{510}\)
e: \(\dfrac{-4}{-75}=\dfrac{4}{75}=\dfrac{4}{75}\)
\(\dfrac{-3}{5}=\dfrac{-3\cdot15}{5\cdot15}=\dfrac{-45}{75}\)
\(\dfrac{8}{25}=\dfrac{8\cdot3}{25\cdot3}=\dfrac{24}{75}\)
f: \(-\dfrac{4}{5}=\dfrac{-4\cdot7}{5\cdot7}=\dfrac{-28}{35}\)
\(\dfrac{6}{7}=\dfrac{6\cdot5}{7\cdot5}=\dfrac{30}{35}\)
A:-43/-81=-215/-405=215/405
-201/135=-603/405
7/9=315/405
B:-1/9=-28/252
-15/28=-135/252
35/0(ko có phép chia cho 0)\(\Rightarrow\)ko thể quy đồng 35/0
Bui Thi Quynh
A:-43/-81=-215/-405=215/405
-201/135=-603/405
7/9=315/405
B:-1/9=-28/252
-15/28=-135/252
35/0(ko có phép chia cho 0)\Rightarrow⇒ko thể quy đồng 35/0