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

a) 47 + 18 – 26 = 39

b) 3 × 8 : 4 = 24 : 4 = 6

c) 5 × 8 – 32 = 40 – 32 = 8

d) 36 : 4 + 17 = 9 + 17 = 26

ket qua la 183

a) Ta thấy:

5=2+3

11=5+3x2

20=11+3x3

32=20+3x4

47=32+3x5

65=47+3x6

Ta có tổng sau:

A=2+5+11+.....+47+65

A=2 + (11 + 32 + 47) + 20 + (5 + 65)

A= 2 + 90 + 20 + 70

A=182

(Hình như đề sai ở chỗ: 95->65)

Vậy: 

A=2+5+11+.....+47+65=182

ta co \(\frac{a}{1+b^2c}=\frac{a\left(1+b^2c\right)-ab^2c}{1+b^2c}=a-\frac{ab^2c}{1+b^2c}\ge a-\frac{ab\sqrt{c}}{2}\)

=>\(\frac{a}{1+b^2c}\ge a-\frac{b\sqrt{a.ac}}{2}\ge a-\frac{b\left(a+ac\right)}{4}\)

cmtt=>dpcm

a: \(A=\left(\dfrac{1}{99}+1\right)+\left(\dfrac{2}{98}+1\right)+...+\left(\dfrac{98}{2}+1\right)+1\)

\(=\dfrac{100}{99}+\dfrac{100}{98}+...+\dfrac{100}{2}+\dfrac{100}{100}\)

\(=100\cdot\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{100}\right)\)=100B

=>B/A=1/100

b: \(A=\left(\dfrac{1}{49}+1\right)+\left(\dfrac{2}{48}+1\right)+\left(\dfrac{3}{47}+1\right)+...+\left(\dfrac{48}{2}+1\right)+\left(1\right)\)

\(=\dfrac{50}{49}+\dfrac{50}{48}+....+\dfrac{50}{2}+\dfrac{50}{50}\)

\(=50\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{50}\right)\)

\(B=\dfrac{2}{2}+\dfrac{2}{3}+\dfrac{2}{4}+...+\dfrac{2}{49}+\dfrac{2}{50}\)

\(=2\left(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{49}+\dfrac{1}{50}\right)\)

=>A/B=25

a) 22+36=58     96−32=64     62−30=32

89−47=42     44+44=88     45−5=40