= 36 đó bn

tich nha!!

1*2*4+2*4*8+4*8*16+8*16*32/1*3*4+2*6*8+4*12*16+8*24*32 = 56744

1*2*4+2*4*8+4*8*16+8*16*32/1*3*4+2*6*8+4*12*16+8*24*32 = 56744

#nhớ tk 

\(B=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}\)

\(2B=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)

\(2B-B=1-\frac{1}{64}\)

\(B=\frac{63}{64}\)

A=1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7

=1-1/2+1/2-1/3+1/3-1/4+1/4

=1/5+1/5-1/6+1/6-1/7

=1-1/7

=6/7

cauB tương tự bạn tự làm nhé 

CHÚC BẠN HỌC TỐT

A = 1/2 + 1/6 + 1/12  + 1/20 + 1/ 30 + 1/42

   = \(\frac{1}{1x2}+\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+\frac{1}{5x6}+\frac{1}{6x7}\)

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

   =\(1-\frac{1}{7}\)

   = \(\frac{6}{7}\)

Ủng hộ mình nha căm ơn nhiều

7) \(A=1^2-2^2+3^2-4^2+...-2004^2+2005^2\)

\(A=\left(-1\right)\left(1^{ }+2\right)+\left(-1\right)\left(3+4\right)+...+\left(-1\right)\left(2003+2004\right)+2005^2\)

\(A=-\left(1+2+3+...+2004\right)+2005^2\)

\(A=-\dfrac{2004.\left(2004+1\right)}{2}+2005^2\)

\(A=-1002.2005+2005^2\)

\(A=2005\left(2005-1002\right)=2005.1003=2011015\)

8) \(B=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)

\(B=\dfrac{\left(2^2-1\right)}{2-1}\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)

\(B=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)

\(B=\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)

\(B=\left(2^{16}-1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)

\(B=\left(2^{32}-1\right)\left(2^{32}+1\right)-2^{64}\)

\(B=\left(2^{64}-1\right)-2^{64}\)

\(B=-1\)

7. 2011015

8. -1

Ghi đầy đủ nha

bn có thể ghi rõ ràng đc ko?

a)\(-\dfrac{3}{7}+\dfrac{5}{13}+\dfrac{3}{7}\) 

=\(\left(-\dfrac{3}{7}+\dfrac{3}{7}\right)+\dfrac{5}{13}\) 

=\(0+\dfrac{5}{13}\) 

=\(\dfrac{5}{13}\)

\(\dfrac{3}{9}+\dfrac{9}{15}+\dfrac{16}{24}=\dfrac{1}{3}+\dfrac{9}{15}+\dfrac{2}{3}=\dfrac{5}{15}+\dfrac{9}{15}+\dfrac{10}{15}=\dfrac{24}{15}=\dfrac{8}{5}\)

\(\dfrac{4}{10}+\dfrac{12}{32}+\dfrac{9}{15}=\dfrac{2}{5}+\dfrac{3}{8}+\dfrac{3}{5}=\dfrac{2}{5}+\dfrac{3}{5}+\dfrac{3}{8}=\dfrac{5}{5}+\dfrac{3}{8}=1+\dfrac{3}{8}=1\dfrac{3}{8}=\dfrac{11}{8}\)

\(\dfrac{1}{6}+\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{18}=\dfrac{3}{18}+\dfrac{9}{18}+\dfrac{6}{18}+\dfrac{1}{18}=\dfrac{19}{18}\)

\(M=1-\left(\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}\right)\)

\(=1-\left(\dfrac{3}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}\right)\)

\(=1-\left(\dfrac{7}{8}+\dfrac{1}{16}+\dfrac{1}{32}\right)\)

\(=1-\left(\dfrac{15}{16}+\dfrac{1}{32}\right)\)

\(=1-\dfrac{31}{32}=\dfrac{1}{32}\)

a) = 25 x 32 + 25 x 47 - 32 x 25 + 32 x 47

   = 25 x 47 - 32 x 47

   = -329

b) = 2 - 12 - 6

    = -16

c) = 2 x (-7) - 10 + 1

    = -14 - 10 + 1

    = -23

d) = -6 - (-1) + (-2)

    = -7