\(a)5 \times \dfrac{7}{5}=7\)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\(b)\dfrac{3}{4} \times \dfrac{7}{9}+\dfrac{1}{4} \times \dfrac{7}{9}\)
\(=\dfrac{7}{9} \times (\dfrac{3}{4}+\dfrac{1}{4})\)
\(=\dfrac{7}{9} \times \dfrac{4}{4}=\dfrac{7}{9}\)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\(c)\dfrac{1}{7} \times \dfrac{5}{9}+\dfrac{5}{9} \times \dfrac{1}{7}+\dfrac{5}{9} \times \dfrac{3}{7}\)
\(=\dfrac{5}{9} \times (\dfrac{1}{7}+\dfrac{1}{7}+\dfrac{3}{7}\)
\(=\dfrac{5}{9} \times \dfrac{5}{7}=\dfrac{25}{63}\)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\(d)\dfrac{4 \times 11 \times 3}{4 \times 9 \times 121}\)
\(=\dfrac{4 \times 3 \times 11}{4 \times 3 \times 3 times 11 \times 11}\)
\(=\dfrac{1}{3 \times 11}=\dfrac{1}{33}\)
a, 5 x 7/5 = 7
b, 3/4 x 7/9 + 1/4 x 7/9
= 7/9 x ( 3/4 + 1/4 )
= 7/9 x 1
= 7/9
c, 1/7 x 5/9 + 5/9 x 1/7 + 5/9 x 3/7
= 1/7x ( 5/9+ 5/9) + 5/9 x 3/7
= 1/7 x 25/81 + 5/21
= 25/567 + 5/21
= 160/567
d, 4x11x3/4 x 9/121
= 44 x 3/4 x 9/121
= 33 x 9/121
= 27/11
a) \(5\times\dfrac{7}{5}=7\)
b) \(\dfrac{3}{4}\times\dfrac{7}{9}+\dfrac{1}{4}\times\dfrac{7}{9}\)
= \(\dfrac{7}{9}\times\left(\dfrac{3}{4}+\dfrac{1}{4}\right)\)
= \(\dfrac{7}{9}\times1\)
= \(\dfrac{7}{9}\)
c) \(\dfrac{1}{7}\times\dfrac{5}{9}+\dfrac{5}{9}\times\dfrac{1}{7}+\dfrac{5}{9}\times\dfrac{3}{7}\)
= \(\dfrac{5}{63}+\dfrac{5}{63}+\dfrac{15}{63}\)
= \(\dfrac{25}{63}\)
d) \(4\times11\times\dfrac{3}{4}\times\dfrac{9}{121}\)
\(=44\times\dfrac{3}{4}\times\dfrac{9}{121}\)
\(=33\times\dfrac{9}{121}\)
\(=\dfrac{297}{121}\)
`5 xx 7/5 = (5xx7)/5 = 35/5 = 7`
`3/4 xx 7/9 + 1/4 xx 7/9`
`=7/9 . (3/4 + 1/4)`
`=7/9 xx 4/4`
`=7/9 .1`
`=7/9`
_________________________________
`1/7 xx 5/9 + 5/9 xx 1/7 + 5/0 . 3/7`
`=5/9 . (1/7 + 1/7 + 3/7)`
`=5/9 . 5/7`
`=(5.5)/(9.7)`
`=25/63`
_________________________
`4/11 xx 3/4 xx 9/121`
\(=\dfrac{4.3.9}{11.4.121}\)
`=27/1331`
a) 5
b) 7 phần 9
c) 25 phần 63
d) 27 phần 11
