8+2+10+80+100+200+100+500x2+1000-1500

= 1000

Hok tốt

:)

Câu hỏi :

8+2+10+80+100+200+100+500x2+1000-1500=?

Trả lời:

8+2+10+80+100+200+100+500x2+1000-1500 = 1000

Trả lời:

8+2+10+80+100+200+100+500x2+1000-1500=?

= 900

100+50:2+75+200:2+400:2+500

= 100 + 25 + 75 + 100 + 200 + 500

= 100 + 100 + 100 + 200 + 500

= 500 + 500

= 1000

100 + 50 : 2 + 75 + 200 : 2 + 400 : 2 + 500

= 100 + 25 + 75 + 100 + 200 + 500

= 125 + 75 + 100 + 200 + 500

= 200 + 100 + 200 + 500

= 300 + 200 + 500

= 500 + 500 

= 1000

100 + 50 : 2 + 75 + 200 : 2 + 400 : 2 + 500

= 100 + 25 + 75 + 100 + 200 + 500

= 125 + 75 + 100 + 200 + 500

= 200 + 100 + 200 + 500

= 300 + 200 + 500

= 500 + 500 

= 1000

50 x 2 + 100 : 10 + 90 + 300 : 2 + 150

= 500

Hok tốt

500 nha bn

Đáp án :

= 500

# Hok tốt !

đề là           I=2^3+2^6+2^9+...+2^99

Ta có : 

         100² > 99 . 100

         101² > 100 . 101

            ..............

         200² > 199. 200

=> A < \(\frac{1}{99.100}+\frac{1}{100.101}+...+\frac{1}{199.200}=\frac{1}{99}-\frac{1}{100}+\frac{1}{100}-\frac{1}{101}+...+\frac{1}{199}-\frac{1}{200}\)

=> A < \(\frac{1}{99}-\frac{1}{200}< \frac{1}{99}\)    \(\left(1\right)\)

Tương tự ta có :

    A > \(\frac{1}{100.101}+\frac{1}{101.102}+...+\frac{1}{200.201}\)

=> A > \(\frac{1}{100}-\frac{1}{101}+\frac{1}{101}-\frac{1}{102}+...+\frac{1}{200}-\frac{1}{201}\)

=> A > \(\frac{1}{100}-\frac{1}{201}>\frac{1}{100}-\frac{1}{200}\)

=>  A > \(\frac{1}{200}\)                   \(\left(2\right)\)

Từ \(\left(1\right);\left(2\right)\)Ta có : 

             \(\frac{1}{200}< A< \frac{1}{99}\)

=> ĐPCM

20x2+20x3+20x4+20 

= 200

20 x 2 + 20 x 3 + 20 x 4 +20

=40 + 60 + 80 + 20

=100+80+20

=180+20

=200

Trả lời :

200

Hokt~

:)

đ/s là

80

hok tot

mong đc k

đáp án

= 80

hok tốt

mong bn k

Trả lời :

10 x 2 + 10 x 2 +100 : 2 -10

= 20 + 20 + 50 -10

= 80

~HT~

a .443

b.152 

(+) \(S=1+2+3+...+200\)

\(\Rightarrow S=\frac{\left(200+1\right)200}{2}=20100\)

(+) \(A=1.2+2.3+....+199.200\)

\(\Rightarrow3A=1.2.\left(3-0\right)+2.3.\left(4-1\right)+.....+199.200.\left(201-198\right)\)

\(\Rightarrow3A=1.2.3-0.1.2+2.3.4-1.2.3+.....+199.200.201-198.199.200\)

\(\Rightarrow3A=199.200.201\)

\(\Rightarrow A=\frac{199.200.201}{3}\)

\(\Rightarrow A=2666600\)

(+) \(B=1^2+2^2+....+200^2\)

\(\Rightarrow B=1\left(0+1\right)+2\left(1+1\right)+3\left(2+1\right)+....+200\left(199+1\right)\)

\(\Rightarrow B=1+1.2+2+2.3+3+.....+199.200+200\)

\(\Rightarrow B=\left(1+2+3+....+200\right)+\left(1.2+2.3+....+199.200\right)\)

\(\Rightarrow B=S+A\)

\(\Rightarrow B=2666600+20100=2686700\)

S = 1 + 2 + 3 + ... + 200

S = (1 + 200).200:2

S = 201.100

S = 20100

A = 1.2 + 2.3 + ... + 199.200

3A = 1.2.(3-0) + 2.3.(4-1) + ... + 199.200.(201-198)

3A = 1.2.3 - 0.1.2 + 2.3.4 - 1.2.3 + ... + 199.200.201 - 198.199.200

3A = 199.200.201

A = 199.200.67

A = 2666600

B = 1² + 2² + 3² + ... + 200²

B = 1.(0 + 1) + 2.(1 + 1) + 3.(2 + 1) + ... + 200.(199 + 1)

B = 0.1 + 1.1 + 1.2 + 1.2 + 2.3 + 1.3 + ... + 199.200 + 1.200

B = (0.1 + 1.2 + 2.3 + ... + 199.200) + (1.1 + 1.2 + 1.3 + ... + 1.200)

B = 2666600 + (200 + 1).200:2

B = 2666600 + 201.100

B = 2666600 + 20100

B = 2686700