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Nhanh rồi mình tích cho

a: \(\dfrac{6}{7}\cdot\dfrac{16}{15}\cdot\dfrac{7}{6}\cdot\dfrac{21}{32}=\dfrac{16}{32}\cdot\dfrac{21}{15}=\dfrac{1}{2}\cdot\dfrac{7}{5}=\dfrac{7}{10}\)

b: \(\dfrac{21}{17}\cdot\dfrac{13}{14}\cdot56\cdot\dfrac{3}{42}=\dfrac{21}{14}\cdot\dfrac{13}{17}\cdot\dfrac{1}{14}\cdot56=\dfrac{78}{17}\)

c: \(=\dfrac{11}{21}\left(\dfrac{7}{4}+\dfrac{5}{4}\right)=\dfrac{11}{21}\cdot3=\dfrac{11}{7}\)

bài 1) thực hiện phép tính

a) \(4^5-81:3^2=1024-9=1015\)

b) \(3^2.22-3^2.12=3^2.2\left(11-6\right)=18.5=90\)

c) \(2^3.15-\left[115-\left(12-5\right)\right]=120-\left(115-12+5\right)=120-115+12-5=12\)

d) \(3.3^2-19^{21}:19^{20}+2010^0=27-19+1=9\)

e)\(7^{25}:\left(7^{21}.46+7^{21}.3\right)=7^{25}:\left(7^{21}.49\right)=\frac{7^{21}.7^4}{7^{21}.49}=\frac{2401}{49}=49\)

bài 2)Tim x

a) 716 - (x - 143) = 695

<=> x - 143 = 716 - 695

<=> x - 143 = 21

<=> x = 21 + 143

<=> x = 164

vậy x = 164

\(\frac{4}{7}.\frac{5}{36}.\frac{21}{25}\)

\(=\frac{4.5.21}{7.36.25}\)

\(=\frac{4.5.7.3}{7.4.9.5.5}\)

\(=\frac{3}{9.5}=\frac{3}{3.3.5}=\frac{1}{15}\)

\(\frac{25}{28}:\frac{15}{14}.\frac{6}{7}\)

\(=\frac{25.14.6}{28.15.7}\)

\(=\frac{5.5.14.6}{28.5.3.7}\)

\(=\frac{5.6}{2.3.7}=\frac{5.2.3}{2.3.7}\)

\(=\frac{5}{7}\)

thank you bạn nam giải bài toán đầu tiên nha

ồ khó thế ?

Ta có:\(x.\frac{1}{5}+x.\frac{4}{5}=2\)

=>\(x.\frac{1}{5}+\frac{4}{5}=2\)

=>\(x.\frac{5}{5}=2\)

=>\(x.1=2\)

=>\(x=2:1\)

=>\(x=2\)

1. X x 1/5 + X x 4/5 = 2

   X x (1/5 + 4/5)     = 2

   X x 1                  = 2

   X                       = 2 : 1

   X                       = 2

2. 18/21 - 19/32 + 3/21 + 13/32

= (18/21 + 3/21) - (19/32 + 13/32)

= 21/21 - 32/32

= 1 - 1

= 0 

\(-\dfrac{3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)=\dfrac{-3}{17}+\dfrac{3}{17}+\dfrac{2}{3}=\dfrac{2}{3}\)

\(\dfrac{-5}{21}+\dfrac{-16}{21}+1=-1+1=0\)

\(\dfrac{-4}{11}\cdot\dfrac{5}{15}\cdot\dfrac{11}{-4}=\dfrac{5}{15}=\dfrac{1}{3}\)

Nhân chia trước cộng trừ sau.

 Chúc bạn học tốt!

Bn làm nhân chia trước cộng trừ sau nhé.

áp dụng công thức bn nhé

chúc bn hộc tốt

a) 2629x21-2526=52683 b) 42567+12312:24=43080 c) 115938:57-57=1977 d) 2/3+5/2-3/4=29/12 e)......tự làm

a) \(\dfrac{1}{3}+\dfrac{4}{3}\times\dfrac{1}{2}=\dfrac{1}{3}+\dfrac{4}{6}=\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{3}{3}=1\)

b) \(\dfrac{3}{5}\times\dfrac{4}{7}:\dfrac{16}{21}=\dfrac{3}{5}\times\dfrac{4}{7}\times\dfrac{21}{16}=\dfrac{12}{35}\times\dfrac{21}{16}=\dfrac{252}{560}=\dfrac{9}{20}\)