a) \(\dfrac{9}{5}+\dfrac{9}{5}:\dfrac{9}{5}\)

\(=\dfrac{9}{5}+\dfrac{9}{5}\times\dfrac{5}{9}\)

\(=\dfrac{9}{5}+1\)

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

b) \(\dfrac{7}{5}-\dfrac{1}{2}\times\dfrac{1}{3}\)

\(=\dfrac{7}{5}-\dfrac{1}{6}\)

\(=\dfrac{42}{30}-\dfrac{5}{30}\)

\(=\dfrac{37}{30}\)

\(a,\dfrac{9}{5}+\dfrac{9}{5}:\dfrac{9}{5}\)

\(=\dfrac{9}{5}+\dfrac{9}{5}\times\dfrac{5}{9}\)

\(=\dfrac{9}{5}+1\)

\(=\dfrac{9}{5}+\dfrac{5}{5}\)

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

\(b,\dfrac{7}{5}-\dfrac{1}{2}\times\dfrac{1}{3}\)

\(=\dfrac{7}{5}-\dfrac{1}{6}\)

\(=\dfrac{42}{30}-\dfrac{5}{30}\)

\(=\dfrac{37}{30}\)

|(5/8-5/14)+(3/8-9/14)|:4/7

=|(5/8+3/8)+(-5/14-9/14)|:4/7

=|1+(-1)|:4/7

=0

`A = ( 5 / 8 - 5 / 14 ) : 4 / 7 + ( 3 / 8 - 9 / 14 ) : 4 / 7`

`A = ( 5 / 8 - 5 / 14 + 3 / 8 - 9 / 14 ) : 4 / 7`

`A = [ ( 5 / 8 + 3 / 8 ) - ( 5 / 14 + 9 / 14 ) ] . 7 / 4`

`A = ( 8 / 8 - 14 / 14 ) . 7 / 4`

`A = ( 1 - 1 ) . 7 / 4 = 0 . 7 / 4 = 0`

\(A=\left(\dfrac{5}{8}-\dfrac{5}{14}\right)\times\dfrac{7}{4}+\left(\dfrac{3}{8}-\dfrac{9}{14}\right)\times\dfrac{7}{4}\)

\(A=\left(\dfrac{5}{8}-\dfrac{5}{14}+\dfrac{3}{8}-\dfrac{9}{14}\right)\times\dfrac{7}{4}\)

\(A=\left(1-1\right)\times\dfrac{7}{4}=0\)

\(\left(\dfrac{6}{11}+\dfrac{5}{11}\right)\times\dfrac{3}{7}=\dfrac{11}{11}\times\dfrac{3}{7}=1\times\dfrac{3}{7}=\dfrac{3}{7}\)

\(\dfrac{3}{5}\left(\dfrac{7}{9}-\dfrac{2}{9}\right)=\dfrac{3}{5}\times\dfrac{5}{9}=\dfrac{1}{3}\)

`( 6 / 11 + 5 / 11 ) xx 3 / 7 = 11 / 11 xx 3 / 7 = 1 xx 3 / 7 = 3 / 7`

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`3 / 5 xx 7 / 9 - 3 / 5 xx 2 / 9 = 3 / 5 xx ( 7 / 9 - 2 / 9 ) = 3 / 5 xx 5 / 9 = 1 / 3`

(6/11+5/11)x3/7

=11/11x3/7

=33/77

3/5x7/9-3/5x2/9

=21/63-6/63

=15/63

a) \(\dfrac{5}{3}+\dfrac{4}{9}:\dfrac{1}{2}=\dfrac{5}{3}+\dfrac{4}{9}\times2=\dfrac{5}{3}+\dfrac{8}{9}=\dfrac{23}{9}\)

b) \(\dfrac{11}{10}-\dfrac{2}{5}:\dfrac{2}{3}=\dfrac{11}{10}-\dfrac{2}{5}\times\dfrac{3}{2}=\dfrac{11}{10}-\dfrac{3}{5}=\dfrac{11}{10}-\dfrac{6}{10}=\dfrac{5}{10}=\dfrac{1}{2}\)

Câu 4 

\(\dfrac{12\times15\times20}{10\times16\times25}=\dfrac{3\times4\times3\times5\times4\times5}{5\times2\times4\times4\times5\times5}=\dfrac{3\times3}{5\times2}=\dfrac{9}{10}\)

Câu 3:

\(a.\dfrac{5}{3}+\dfrac{4}{9}:\dfrac{1}{2}=\dfrac{5}{3}+\dfrac{8}{9}=\dfrac{15}{9}+\dfrac{8}{9}=\dfrac{23}{9}\)

\(b.\dfrac{11}{10}-\dfrac{2}{5}:\dfrac{2}{3}=\dfrac{11}{10}-\dfrac{3}{5}=\dfrac{11}{10}-\dfrac{6}{10}=\dfrac{5}{10}=\dfrac{1}{2}\)

Câu 4:

\(\dfrac{12\times15\times20}{10\times16\times25}=\dfrac{3\times3\times1}{2\times1\times5}=\dfrac{9}{10}\)

\(A=\left(x-1\right)^2+8\ge8\\ A_{min}=8\Leftrightarrow x=1\\ B=\left(x+3\right)^2-12\ge-12\\ B_{min}=-12\Leftrightarrow x=-3\\ C=x^2-4x+3+9=\left(x-2\right)^2+8\ge8\\ C_{min}=8\Leftrightarrow x=2\\ E=-\left(x+2\right)^2+11\le11\\ E_{max}=11\Leftrightarrow x=-2\\ F=9-4x^2\le9\\ F_{max}=9\Leftrightarrow x=0\)

 a) 3² . 5³ + 9² = 9 . 125 + 81

= 1 125 + 81 = 1 206

b) 8³ : 4² - 5² = 512 : 16 - 25 = 32 - 25 = 7

c) 3³ . 9² - 5².9 + 18 : 6 = 27 . 81 - 25 . 9 + 3

= 2 187 - 225 + 3 = 1 962 + 3 = 1 965

 a) 3² . 5³ + 9² = 9 . 125 + 81

= 1 125 + 81 = 1 206

b) 8³ : 4² - 5² = 512 : 16 - 25 = 32 - 25 = 7

c) 3³ . 9² - 5².9 + 18 : 6 = 27 . 81 - 25 . 9 + 3

= 2 187 - 225 + 3 = 1 962 + 3 = 1 965

\(a,=\dfrac{5}{6}+\dfrac{6}{7}\\ =\dfrac{35}{42}+\dfrac{36}{42}=\dfrac{71}{42}\\ b,=\dfrac{5}{6}+\dfrac{4}{9}\\ =\dfrac{15}{18}+\dfrac{8}{18}=\dfrac{23}{18}\)

C

a) 32 - 6 . (8 - 2³) + 18 =  32 - 6 . (8 - 8) + 18

= 32 - 6 . 0 + 18 = 32 + 18 = 50

b) (3 . 5 - 9)³ . (1 + 2 . 3)² + 4²

= (15 - 9)³ . (1 + 6)² + 4²

= 6³ . 7² + 4² = 216 . 49 + 16 = 10 584 + 16 = 10 600

a) 32 - 6 . (8 - 2³) + 18 =  32 - 6 . (8 - 8) + 18

= 32 - 6 . 0 + 18 = 32 + 18 = 50

b) (3 . 5 - 9)³ . (1 + 2 . 3)² + 4²

= (15 - 9)³ . (1 + 6)² + 4²

= 6³ . 7² + 4² = 216 . 49 + 16 = 10 584 + 16 = 10 600