a: \(\frac{3^{10}\cdot\left(-5\right)^{21}}{\left(-5\right)^{20}\cdot3^{12}}=\frac{-3^{10}\cdot5^{21}}{3^{12}\cdot5^{20}}=\frac{-5}{3^2}=-\frac59\)

b: \(\frac{-11^5\cdot13^7}{11^5\cdot13^8}=\frac{-11^5}{11^5}\cdot\frac{13^7}{13^8}=-\frac{1}{13}\)

c: \(2^{10}\cdot3^{10}-2^{10}\cdot3^9\)

\(=2^{10}\cdot3^9\cdot\left(3-1\right)\)

\(=2^{11}\cdot3^9\)

Ta có: \(\frac{2^{10}\cdot3^{10}-2^{10}\cdot3^9}{2^9\cdot3^{10}}\)

\(=\frac{2^{11}\cdot3^9}{2^{10}\cdot3^9}=2\)

d: \(5^{11}\cdot7^{12}+5^{11}\cdot7^{11}\)

\(=5^{11}\cdot7^{11}\left(7+1\right)=5^{11}\cdot7^{11}\cdot8\)

\(5^{12}\cdot7^{12}+9\cdot5^{11}\cdot7^{11}\)

\(=5^{11}\cdot7^{11}\left(5\cdot7+9\right)\)

\(=5^{11}\cdot7^{11}\left(35+9\right)=5^{11}\cdot7^{11}\cdot44\)

Ta có: \(\frac{5^{11}\cdot7^{12}+5^{11}\cdot7^{11}}{5^{12}\cdot7^{12}+9\cdot5^{11}\cdot7^{11}}\)

\(=\frac{5^{11}\cdot7^{11}\cdot8}{5^{11}\cdot7^{11}\cdot44}=\frac{8}{44}=\frac{2}{11}\)

Ta tính nhẩm như sau:

3x4=12     2x5=10    5x3=15     4x2=8

12:3=4      10:2=5    15:3=5      8:2=4

12:4=3      10:5=2     15:5=3     8:4=2

a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)

\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)

\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)

\(=\dfrac{-1621}{126}\)

b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)

\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)

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

\(=-\dfrac{49}{20}\)

Phương pháp giải:

Nhẩm giá trị của phép nhân và phép chia rồi điền kết quả vào chỗ trống.

Lời giải chi tiết:

Q=(2^9.3+2^9.5):2^12

Đặt A=2^9.3+2^9.5

      A=2^9.(3+5)

      A=2^9.8

Mặt khác:8=2^3

=>A=2^9.2^3

     A=2^12

Theo đề bài ta có Q=(2^9.3+2^9.5):2^12

=>Q=2^12:2^12

    Q=1

Nhìn dài dòng thế thôi chứ đơn giản lắm.Nếu thấy đúng thì cho mình nhé!

a)\(\frac{3^{10}.\left(-5\right)^{21}}{\left(-5\right)^{20}.3^{12}}=\frac{-5}{9}\)

b)\(\frac{\left(-11\right)^5.13^7}{11^5.13^8}=-\frac{1}{13}\)

c)\(\frac{2^{10}.3^{10}-2^{10}.3^9}{2^9.3^{10}}=\frac{2^{10}.3^9\left(3-1\right)}{2^9.3^{10}}=2\)

d(\(\frac{5^{11}.7^{12}+5^{11}.7^{11}}{5^{12}.7^{12}+9.5^{11}.7^{11}}=\frac{5^{11}.7^{11}\left(7+1\right)}{5^{11}.7^{11}\left(35+9\right)}=\frac{1}{6}\)

giúp mk vs nha

Câu 1: A

Câu 2: B

Câu 3: A

Câu 4: A

Đề bài là tính hả bạn?

ukm bn

\(a,-\frac{4}{7}+\left(-\frac{2}{3}+\frac{3}{7}\right)=-\frac{4}{7}-\frac{2}{3}+\frac{3}{7}=-\frac{4}{7}+\frac{3}{7}-\frac{2}{3}=-\frac{1}{7}-\frac{2}{3}=-\frac{17}{21}\)

\(b,-\frac{3}{10}\cdot\frac{5}{12}+-\frac{3}{10}\cdot\frac{7}{12}+5\cdot\frac{3}{10}=\frac{3}{10}\cdot-\frac{5}{12}+\frac{3}{10}\cdot-\frac{7}{12}+5\cdot\frac{3}{10}=\frac{3}{10}\cdot\left(-\frac{5}{12}-\frac{7}{12}+5\right)\)

\(=\frac{3}{10}\cdot4=\frac{6}{5}\)

ti ck nha

đúng đó

xin đó

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a, -4/7 + (-2/3 + 3/7 )

= -4/7 + (-2/3) + 3/7

= -4/7 + 3/7 + (-2/3)

= -1/7 + -14/21

= -3/21 + -14/21

= -17/21

b, -3/10 . 5/12 + -3/10 . 7/12 + 5. - 3/10

-3/10.(5/12 + 7/12 + 60/12)

-3/10.6

-18/10= -9/5