10 x 10 = 100 

9 x 9 = 81 

8 x 8 = 64 

7 x 7 = 49 

6 x 6 = 36 

5 x 5 = 25 

4 x 4 = 16 

3 x 3 = 9 

2 x 2 = 4 

1 x 1 = 1

10 . 10 =10²=100
9 . 9 =9²=81
8 . 8 =8²=64
7 . 7 =7²=49
6 . 6 =6²=36
5 . 5 =5²=25
4 . 4 =4²=16
3 . 3 =3²=9
2 . 2 =2²=4
1 . 1 =1²=1

10+9-8+7-6+5-4+3-2+1-0

= 10 +[(9 - 8) + (7 - 6) + (5 - 4) + (3 - 2) + (1 - 0)]

= 10 + [1 + 1 + 1 + 1 + 1]

= 10 + 1 x 5

= 10 + 5

= 15

15

Số số hạng của dãy số là:

10-0+1=11(số)

Tổng của dãy số là: \(\left(10+0\right)\times\frac{11}{2}=10\times\frac{11}{2}=5\times11=55\)

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1+2+3+4+5+6+7+8+9+10+11=66

1+2+3+4+5+6+7+8+9+10+11=66

Tui không biết nha giúp tui làm

550 bạn nhé

[(1+9)+(2+8)+(3+7)+(4+6)+5]x2

=(10+10+10+10+5)x2

=45x2

=90

50x2+2x10

=2x(50+10)

=2x60

=120

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)

1 + 1 + 2 + 2 + 3 + 3 + 4 + 4 + 5 + 5 + 6 + 6 + 7 + 7 + 8 + 8 + 9 + 9 +10 +10  

= (1+9) + (1+9) + (2+8) + (2+8) + (3+7) + (3+7) + (4+6) + (4+6) + (5+5) + 10+10

= 10 + 10 +10 + 10 +10 +10 +10 +10 + 10 + 10 +10

= 10 x 11

= 110

110

1 - 2 + 3 - 4 + 5 - 6 + 7 - 8 + 9

= (9 - 8) + (7 - 6) + (5 - 4) + (3 - 2) + 1

= 1 + 1 + 1 + 1 + 1

= 1 x 5

= 5

5

1+1-2+2-3+3-4+4-5+5-6+6-7+7-8+8-9+9-10=-8

bằng 10 nha