There is a sequence {an} which is composed of the following rules: 11, 12, 21, 13, 22, 31, 14, 23, 32, 41, 15, 24, 33, 42, 51, 16 Question: (1) what is 2750 in the sequence? (2) Which score is item 200?

There is a sequence {an} which is composed of the following rules: 11, 12, 21, 13, 22, 31, 14, 23, 32, 41, 15, 24, 33, 42, 51, 16 Question: (1) what is 2750 in the sequence? (2) Which score is item 200?

According to the meaning of the question, we can get 11, (12, 21), (13, 22, 31), (14, 23, 32, 41), (15, 24, 33, 42, 51), 16 If the numerator denominator is added to N, this group has n-1 numbers, (1) ∵ 50 + 27 = 77, the group in which ∵ 2750 is located has 76 numbers, then the former group has 75 numbers
From land a to land B, it takes 10 hours for large trucks and 8 hours for small cars, which are () percent faster than trucks
（10-8）÷10
=2÷10
=0.2
=20%
---------------------------Big decrease divided by ratio----------------------------
Some mathematical problems, simple calculation requirements
Question 1: the reciprocal of 1.2 is () and () are reciprocal
Question 2: 0.56 × 4.8 + 0.44 × 24 / 5
Question 3: 3 / 4x + 3 / 4x = 1 / 8
Question 4: 102 minus 7.5 minus two and one-half
Question 5: 3 / 4x + 3 / 4x = 1 / 8
1: The reciprocal of 1.2 is (5 / 6), and (6 / 5) are reciprocal
2:0.56×4.8+0.44×24/5=4.8
3：3/4X+3/4X=1/8,x=1/12
4: 102 minus 7.5 minus two and a half, 92
5：3/4X+3/4X=1/8,
x=1/12
6: The diameter of the circle is 2cm, drawing circle, circle area is the largest
Question 1: the reciprocal of 1.2 is (5 / 6), and (6 / 5) are reciprocal
Question 2: 0.56 × 4.8 + 0.44 × 24 / 5 = 4.8
Question 3: 4x = 3 / 12
Question 4: 102 minus 7.5 minus two and a half, 92
Question 5: 3 / 4x + 3 / 4x = 1 / 8, x = 1 / 12
The reciprocal of 1.2 is (5 / 6), and (6 / 5) are reciprocal
0.56×4.8+0.44×24/5=4.8
3/4X+3/4X=1/8，x=1/12
102 minus 7.5 minus two and a half, 92
3/4X+3/4X=1/8，x=1/12
Question 1-1.2 5 / 6
Question 2 4.8
One twelfth of the third question
Question 4 92
One twelfth of the fifth question
According to certain rules of sequence
What's the next number for 19?
It's 28, calculated by 9 + 19 = 28
Twenty-eight
A car from a to B, two hours 180 kilometers, just two-thirds of the whole line. At this speed, how many hours to complete the whole line?
2 ÷ (2 / 3) = 3 hours
How to solve these three math problems
3x-12 = half x + 7
(3.07 * 10 square five) divided by (2.5 * 10 square three)
-y（y+6）+-3（y+6）
1. First, multiply both sides by 2:6x-24 = x + 14 at the same time to get: 5x = 38 solution: x = 7.62, does it mean the quintic power of 3.07 times 10 divided by (the third power of 2.5 times 10)? If it is, then the result is directly reduced to the third power of 10 = 3.07 / 2.5, and then multiplied by 100 = 122.83, is it a plus or minus sign before the middle 3? Calculate according to the minus sign
First question: 6x-24 = x + 14
5X=38
X=7.6
Question 3: - Y (y + 6) - 3 (y + 6)
=(y+6)(-y-3)
The title of the second question is not clear
The first one is good
4,16,36,64, < >, 144196, < > 10th number, < > 100th number
3,2,1,0,-1,-2,-3,< >,
One
100, the square of ten
400 20 square meters
40000200 square meters
2.-4,-5,-6
100 20^2 200^2
-4 -5 -6
1. The nth number is (2n) ^ 2
So the tenth number: 400
The 100th number: 40000
2.:??-4,-5,-6
There are 44 three wheeled agricultural vehicles, four wheeled medium-sized buses and six wheeled trucks in a parking lot, and there are 171 wheels. It is known that four wheeled medium-sized buses are two times less than six wheeled trucks, so how many three wheeled agricultural vehicles are there in this parking lot?
There are x large trucks with six wheels, there are (2x-1) vehicles with four wheels, and there are (2x-1) vehicles with four wheels, and there are 44-x - (2x-1) = 44-3x + 1 agricultural vehicles with three wheels, and there are 44-x - (2x-1) = 44-x - (2x-1) = 44-3x + 1. The equation can be derived from the meaning of the title: the equation: 6x + 4 × (2X-4 × (2X-4 (2x-1-1) (2x-1-1) + 3 × (2x (2x-1) + 3 × (2x (2x-3-3x-3x-1) + 3 (44-3x (44-3x (44-3x-3x-3x-3x-3x + 1) + (44-3x-3x-3x-3x + 1) + (2x-1) + (2x-1) + (2x-1) + -3x-1 nbsp; & nbsp;            5x+131=171，                   5x+131-131=171-131，                         &A & nbsp; & nbsp; & nbsp; & nbsp; = 8 cars in total
Simple operation is required
20*20\21+20\21+5\8
=
=
=
……
（21-1）*20/21+20/21*1+5/8
=21*20/21-1*20/21+1*20/21+5/8
=20-20/21+20/21+5/8
=20+5/8
=20 and 5 / 8
=20（20+1）/21+5/8
=20+5/8
=20.625
=(20+1)*20\21+5\8
=20+5\8
=20.625
(20+1-1)*20/21+(20+1-1)/21+5/8
=20-20/21+1-1/21+5/8
=20+5/8
=165/8
Original formula = 20 / 21 * (20 + 1) + 5 / 8
=20+5/8
=165/8
1/(1*20)+1/(2*3)+1/(3*4).+1/(2009*2010)=?
1/(1*2)+1/(2*3)+1/(3*4).+1/(2009*2010)
=[(1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/2009-1/2010)]
=(1-1/2010)
=2009/2010
1/(1*2)+1/(2*3)+1/(3*4)....+1/(2009*2010)
=1-1/2+1/2-1/3+1/3-1/4… +1/2009-1/2010
=1-1/2010
=2009/2010
("/" denotes a fractional line)