K^o tính dc vì ra số âm -58³

(9^9.8^2)/(3^15.2^3.2^3)

(3^18.2^6)/(3^18.2^3)

2^3

\(C=\frac{9^9.8^2}{27^5.6^3}\)

   \(=\frac{\left(3^2\right)^9.2^6}{\left(3^3\right)^5.\left(2.3\right)^3}\)

   \(=\frac{3^{18}.2^6}{3^{15}.2^3.3^3}\)

    \(=\frac{3^{18}.2^3.2^3}{3^{18}.2^3}=2^3=8\)

\(C=\frac{9^9.8^2}{27^5.6^3}\)

\(C=\frac{\left(3^2\right)^9.\left(2^3\right)^2}{\left(3^3\right)^5.\left(2.3\right)^3}\)

\(C=\frac{3^{18}.2^6}{3^{15}.2^3.3^3}\)

\(C=\frac{3^{18}.2^6}{3^{18}.2^3}\)

\(C=\frac{2^6}{2^3}\)

\(C=2^3\)

\(C=8\)

\(S=9,8+8,7+7,6+...+2,1-1,2-2,3-3,4-...-8,9\)

\(=\left(9,8-8,9\right)+\left(8,7-7,8\right)+...+\left(2,1-1,2\right)\)

\(=0,9+0,9+...+0,9\)

\(=0,9\times8=7,2\)

a) \(-\left(76-35+15\right)+\left[18-27+\left(-17\right)\right]\)

\(=-76+35+15+18-27-17\)

\(=-52\)

b) \(167+\left[127-235-\left(-16\right)\right]+\left(-67\right)\)

\(=167+127-235+16-67\)

\(=8\)

c) \(\left(-19\right)+165-\left[27+\left(-21\right)-\left(+72\right)\right]\)

\(=\left(-19\right)+165-27+21+72\)

\(=212\)

d) \(89.\left(-2\right)+\left[20+\left(-2\right).\left(-5\right)-85\right]\)

\(=\left(-178\right)+\left(20+10-85\right)\)

\(=\left(-178\right)+20+10-85\)

\(=-233\)

\(\frac{3}{2}+\frac{3}{2.3}+\frac{3}{3.4}+...+\frac{3}{17.18}\)

\(=\frac{3.1}{1.2}+\frac{3}{2.3}+\frac{3}{3.4}+...+\frac{3}{17.18}\)

\(=3.\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{17.18}\right)\)

\(=3.\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-...+\frac{1}{17}-\frac{1}{18}\right)\)

\(=3.\left(1-\frac{1}{18}\right)\)

\(=3.\frac{17}{18}\)

\(=\frac{17}{6}\)

cùng hình nè

đặt A =\(\frac{3}{2}\)+\(\frac{3}{3x4}\)+...........+\(\frac{3}{17x18}\)

nhân cả 2 vế với \(\frac{1}{3}\)

A x \(\frac{1}{3}\)= \(\frac{1}{2}\)+\(\frac{1}{3x4}\)+..........+\(\frac{1}{17x18}\)

A x \(\frac{1}{3}\) =\(\frac{1}{2}\)+\(\frac{1}{3}\)-\(\frac{1}{4}\)+...........+\(\frac{1}{17}\)-\(\frac{1}{18}\)

A x \(\frac{1}{3}\)=\(\frac{1}{2}\)+\(\frac{1}{3}\)-\(\frac{1}{18}\)

A x \(\frac{1}{3}\)=\(\frac{7}{9}\)

A = \(\frac{7}{9}\):\(\frac{1}{3}\)

A= \(\frac{7}{3}\)

2.3x3,4+2,3x5,6x2,3 =2,3x3,4+2,3x5,6x2,3x1 =2,3x(3,4+5,6+1) =2,3x10 =23

Giải 

=2,3 x 3,4 + 2,3 x 5,6 + 23 x 1

= 2,3 x (3,4 + 5,6 + 1)

=2,3 x 10

=23 

23 nha bnja

Bài này là cơ bản luôn đó:
= 3.(1/1.2 + 1/2.3+...)
= 3.(1/1-1/2+1/2-1/3...)
(tự viết nốt và tính)

\(M=\dfrac{1}{2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+\dfrac{1}{4\cdot5}+\dfrac{1}{5\cdot6}+\dfrac{1}{6\cdot7}\)

\(M=\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+\dfrac{1}{4\cdot5}+\dfrac{1}{5\cdot6}+\dfrac{1}{6\cdot7}\)

\(M=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}\)

\(M=1-\dfrac{1}{7}\)

\(M=\dfrac{6}{7}\)

tham khảo

https://hoc24.vn/cau-hoi/123134145156167.5003535458609#:~:text=l%C3%BAc%2021%3A02-,1,14,-12.3%2B13.4%2B14.5

vào đi 

refer

https://hoc24.vn/cau-hoi/123134145156167.5003535458609#:~:text=l%C3%BAc%2021%3A02-,1,14,-12.3%2B13.4%2B14.5

2.3x3,4+2,3x5,6x2,3 =2,3x3,4+2,3x5,6x2,3x1 =2,3x(3,4+5,6+1) =2,3x10 =23

= 2.3 + 2.6 + 2.3 + 2.15 + 2.3

= 2.(3+6+3+15+3)

= 2.30

= 60

=2,3 x 3,4 + 2,3 x 5,6 + 23 x 1

= 2,3 x (3,4 + 5,6 + 1)

=2,3 x 10

=23