giải phương trình

x^{2 ₊} x + \(\sqrt{x^3_{ }-1}\) = 2x\(\sqrt{x}\)

A = 1 + 4 + 9 + .... + 2401 + 2500

=> A = 12 + 22 + 32 + 42 + ..... + 492 + 502
=> A = 1.1 + 2.2 + 3.3 + ..... + 49.49 + 50.50

=> A = 1.( 2 - 1 ) + 2.( 3 - 1 ) + 3.( 4 - 1 ) + ..... + 49.( 50 - 1 ) + 50.( 51 - 1 )

=> A = 1.2 - 1 + 2.3 - 2 + 3.4 - 3 + ..... + 49.50 - 49 + 50.51 - 50

=> A = ( 1.2 + 2.3 + 3.4 + .... + 49.50 + 50.51 ) - ( 1 + 2 + 3 + ..... + 49 + 50 )

=> A = \(\frac{50.51.52}{3}-\frac{50.\left(50+1\right)}{2}\)
=> A = 44200 - 1275

=> A = 42925

điền giới từ vào chỗ trống

1. they are arguing ... who's going to win the world cup

2. he died... a heart attack

3. my father is a retied worker and is now living ... his person

4. the tallest buildings in london are small ... comparison... those in New York

5. he often goes to work ... motorbike, but ... bad weather he goes .... his company' s car

6. the teacher was listened to ... a great interest

7. i saw him .... the corner .... Phan Dinh Phung street and Tran Hung Dao street

8. coming to our area, visitors can take guided tours... the jungle or swim ... the blue sea

dùng từ gợi ý viết thành câu hoàn chỉnh

1. I/you/take/work/avoid/traffic jam.

2.if he/work/ over time/He earn /much /I

3 I /clear off/ table /if/ they /eat /dinner.

4 We /fly / earth /if /it stop/ spin

5 you/better/listen /cassette player/more often/ it want/ improve/ English

bài kia là mk giải tắt, còn viết đầy đủ phải là:

169 chia hết cho 3n+1

=>3n+1 thuộc Ư(169)

=>3n+1 thuộc {-169;-13;-1;1;13;169}

*nếu 3n+1=-169

=>ko có giá trị n thỏa mãn

*nếu 3n+1=-13

=>ko có giá trị n thỏa mãn

*nếu 3n+1=-1

=>ko có giá trị n thỏa mãn

*nếu 3n+1=1

=>n=0

*nếu 3n+1=13

=>n=4

*nếu 3n+1=169

=>n=56

Vậy n thuộc {0;4;56}