He thinks reading is very interesting

He thinks reading is very interesting

He thinks that reading books is very interesting.

Some students are in the classroom

1) Some students are in the classroom.
2) There are some students in the classroom.

The students left the classroom as soon as possible

Students left the classroom as soon as possible.

Calculation: 2 / 3 * 5 + 1 / 5 * 7 + 1 / 7 * 9 + 1 / 9 * 11 + 1 / 11 * 13

2/3*5+1/5*7+1/7*9+1/9*11+1/11*13
=1/15+1/2(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13)
=1/15+1/2(1/3-1/13)
=38/195

In known sequence {an}, A1 = 2, an = a (n-1) / 2A (n-1) + 1, find the general term formula an

An = a (n-1) / [2A (n-1) + 1] 1 / an = [2A (n-1) + 1] / a (n-1) = 2 + 1 / a (n-1) 1 / an-1 / a (n-1) = 2, is a fixed value. A1 = 21 / A1 = 1 / 2 sequence {1 / an} is an arithmetic sequence with 1 / 2 as the first term and 2 as the tolerance. The general formula of 1 / an = 1 / 2 + 2 (n-1) = 2n-3 / 2 = (4n-3) / 2An = 2 / (4n-3) sequence {an} is an = 2 /

Mingming's new room is going to be paved with square bricks. If you use 0.09 square meters of square bricks, you need 160 pieces. If you use 0.4 meters of square bricks, how many pieces?

How many pieces are needed: 0.09 × 160 ^ (0.4 × 0.4), = 0.09 × 160 ^ 0.16, = 14.4 ^ 0.16, = 90 (pieces). A: if you use square bricks with side length of 0.4m, you need 90 pieces

"Fifty six nations and fifty six flowers". What do you think of when you read this sentence
Write in detail (⊙ o ⊙) oh

"56 nationalities and 56 flowers" here we compare 56 Chinese nationalities to flowers. I think of many flowers blooming in a hundred flower garden. The roots of those flowers are connected and never separate

How to calculate Sin & # 178; π / 3-cos & # 178; π / 4

sin²π/3-cos²π/4
=(√3/2)²-(√2/2)²
=3/4-2/4
=1/4

The three sides of a right triangle below are 3cm, 4cm, 5cm, perimeter () and area ()

There is a right triangle at the bottom. Its three sides are 3cm, 4cm, 5cm, 12cm in circumference and 6cm in area

1. Given that the line ax + by + C = 0 and the circle x + y = 1 are compared with two points a and B, and the module of AB = root 3, then the vector OA × ob =?
2. The volume of a triangular pyramid p-abc is 2 if the side edges of p-abc are perpendicular to each other and the side areas are 6, 4 and 3 respectively

1. The angle between OA and ob is 120 degrees
2、1/2xy=6
1/2yz=4
1/2zx=3
xy=12
x/y=3/4
So x = 3, y = 4, z = 2
Volume = 1 / 3 * s * H = 1 / 3 * (1 / 2 * 3 * 4) * 2 = 4