a: \(A=\dfrac{63-48-70}{84}:\dfrac{-3\cdot84+4\cdot60+5\cdot70}{840}\cdot\dfrac{1-14}{12}\)

\(=\dfrac{-55}{84}\cdot\dfrac{840}{338}\cdot\dfrac{-13}{12}=\dfrac{55}{1}\cdot\dfrac{10}{338}\cdot\dfrac{13}{12}=\dfrac{275}{156}\)

b: \(=-234\cdot123+123\cdot4356-123\cdot2312+234\cdot123-234\cdot2312+2312\cdot234+2312\cdot123\)

\(=123\cdot4356-123\cdot2312+123\cdot2312=123\cdot4356=535788\)

a) 1 ≤  x ≤ 5 => x ∈ {1;2;3;4;5}

b) -3 ≤  x ≤ 4 =>x ∈ {0;1;2;3;4}

c) 4 ≤  x ≤ 9 => x ∈ {4;5;6;7;8;9}

a)  5 6 + 1 6 ≤ x ≤ 13 4 + 14 8 ⇔ 1 ≤ x ≤ 5 ⇔ x ∈ 1 ; 2 ; 3 ; 4 ; 5

b)  − 5 6 + 8 3 + 29 − 6 ≤ x ≤ − 1 2 + 2 + 5 2 ⇔ − 3 ≤ x ≤ 4 ⇔ x ∈ − 3 ; − 2 ; − 1 ; 0 ; 1 ; 2 ; 3 ; 4

c)  79 15 + 7 5 + − 8 3 ≤ x ≤ 10 3 + 15 4 + 23 12 ⇔ 4 ≤ x ≤ 9 ⇔ x ∈ 4 ; 5 ; 6 ; 7 ; 8 ; 9

12) \(\sqrt{15-6\sqrt{6}}+\sqrt{35-12\sqrt{6}}\)

\(=3-\sqrt{6}+3\sqrt{3}-2\sqrt{2}\)

13) \(\sqrt{46-6\sqrt{5}}-\sqrt{29-12\sqrt{5}}\)

\(=3\sqrt{5}-1-2\sqrt{5}+3\)

\(=\sqrt{5}+2\)

giải tắt quá á đọc ko hiểu ạ

a: =125-24-75

=50-24

=26

a) 5

b) 11/6

a) \(-\dfrac{2}{9}-\dfrac{5}{12}\)

\(=-\dfrac{8}{36}-\dfrac{15}{36}\)

\(=-\dfrac{23}{36}\)

b) \(2,25-\left(-\dfrac{6}{25}\right)\)

\(=2,25+\dfrac{6}{25}\)

\(=2,49\)

c) \(\dfrac{5}{12}-\left(-\dfrac{7}{6}\right)\)

\(=\dfrac{5}{12}+\dfrac{14}{12}\)

\(=\dfrac{19}{12}\)

a) \(\dfrac{-2}{9}-\dfrac{5}{12}=\dfrac{-8}{36}-\dfrac{15}{36}=\dfrac{-23}{36}\)

b) \(2,25-\left(-\dfrac{6}{25}\right)=2,25+\dfrac{6}{25}=\dfrac{225}{100}+\dfrac{6}{25}=\dfrac{225}{100}+\dfrac{24}{100}=\dfrac{249}{100}\)

c) \(\dfrac{5}{12}-\left(-\dfrac{7}{6}\right)=\dfrac{5}{12}+\dfrac{7}{6}=\dfrac{5}{12}+\dfrac{14}{12}=\dfrac{19}{12}\)

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