265+5x2+56x10+56

=265+10+56x10+56

=265+56x(10+10)

=265+56x20

=265+1120

=1385

56*4*56*3+56*2+56=75432

37800

56.4.56.3+56.2+56

=56.(56.3.4+2+1)

=56.675

=37800

127.(27 - 56) - 27.(127 - 56)

= 127.27 - 127.56 - 27.127 + 27.56

= (127.27 - 27.127) - (127.56 - 27.56)

= 0 - 56(127 - 27)

= 0 - 56.100

= 0 - 5600

= -5600

127.(27-56)- 27 . (127 - 56)

\(=\left(127-127\right)\cdot\left(27-27\right)\cdot\left(56-56\right)\)

\(=0\cdot0\cdot0\)

\(=0\)

cach giai rui mk tich cho

Đổi: 75%=3/4

       25%=1/4

3/4x56+1/2x28-1/4x224

=3/4x56+(1/2:2)x(28x2)-(1/4x4)x(224:4)

=3/4x56+     1/4x    56  -     1     x    56

=(3/4+1/4-1)x56

=   1-1         x56

=     0          x56

=         0.

 75% *56 +1/2 *28-25%*224=0

=94745,21212

Nguyễn Trung Hiếu nó copy

Đặt A = 1/2 + 5/6 + ... + 89/90

9 - A = 1- 1/2 + 1- 5/6 + ... + 1- 89/90

 9 -A = 1/2 + 1/6 + ... + 1/90

9 -A = 1/1.2 + 1/2.3 + ... + 1/9.10

9-A = 1/1 - 1/2 + 1/2 - 1/3 +....  + 1/9 - 1/10

9 - A = 1/1 - 1/10

9- A = 9/10

=> A = 9 - 9/10

=> A = 81/10 

số cần tìm là 81/10

\(56+\left(-29\right)+\left(-7\right)+28+13+\left(-35\right)\)

\(=\)\(27+\left(-7\right)+28+13+\left(-35\right)\)

\(=\)\(20+28+13+\left(-35\right)\)

\(=\)\(48+13+\left(-35\right)\)

\(=\)\(61+\left(-35\right)\)

\(=\)\(26\)

\(\frac{8}{9}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-\frac{1}{30}-\frac{1}{20}-\frac{1}{12}-\frac{1}{6}-\frac{1}{2}\)

\(=\frac{8}{9}-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}\right)\)

\(=\frac{8}{9}-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{8.9}\right)\)

\(=\frac{8}{9}-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+....+\frac{1}{8}-\frac{1}{9}\right)\)

\(=\frac{8}{9}-\left(1-\frac{1}{9}\right)\)

\(=\frac{8}{9}-\frac{8}{9}=0\)

\(\frac{8}{9}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-\frac{1}{30}-\frac{1}{20}-\frac{1}{12}-\frac{1}{6}-\frac{1}{2}\)

\(=\frac{8}{9}-\left(\frac{1}{72}+\frac{1}{56}+\frac{1}{42}+\frac{1}{30}+\frac{1}{20}+\frac{1}{12}+\frac{1}{6}\right)\)

\(=\frac{8}{9}-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}\right)\)

\(=\frac{8}{9}-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}\right)\)

\(=\frac{8}{9}-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}\right)\)

\(=\frac{8}{9}-\left(1-\frac{1}{9}\right)\)

\(=\frac{8}{9}-\frac{8}{9}\)

\(=0\)