What rules do you find by observing the following formulas 1*3+1=2*2 2*4+1=3*3 3*5+1=4*4 …… Do you have similar questions

What rules do you find by observing the following formulas 1*3+1=2*2 2*4+1=3*3 3*5+1=4*4 …… Do you have similar questions

It is deduced that the square of a number is the product of two adjacent numbers plus 1

There are the following five formulas. If you observe them carefully, can you find the rules of these formulas?
2 + 2 = 2 * 2,3 + 1.5 = 3 * 1.5,6 + 1.2 = 6 * 1.2,9 + 1125 = 9 * 1.125,11 + 1.1 = 11 * 1.1 ellipsis

Language expression: the sum of two numbers is equal to the product of two numbers
Formula expression: n + n / (n-1) = n * [n / (n-1)]

Please observe the following formulas carefully, and then write the fourth and fifth formulas according to the rules you found
1.√16=√1x16=√1x4²=√1x√4²=1x4=4
2.√32=√2x16=√2x4²=√2x√4²=√2x4=4√2
3.√48=√3x16=√3x4²=√3x√4²=√3x4=4√3
4.√64=__________________
5.√80=_____________________

=Root (4 × 16) = root 4 × root (4 ^ 2) = 2 × 4 = 8
=Radical (5 × 16) = radical 5 × radical (4 ^ 2) = radical 5 × 4 = 4 radical 5

Simple calculation: 1.5 * 8.6 + 15 * 0.13 + 0.15

0.15*(86+13+1)=0.15*100=15

1+2+3+4+5+6+7+8+9…… +How simple is 20 = a few

One plus 19, two plus 18, come on

How to calculate 20.9 + 10.5 ÷ (5.5-4.8)?

20.9+10.5÷(5.5-4.8)
=20.9+105/10*10/7
=20.9++13
=33.9

(- 8) + (- 9) =? And other 20 questions, except for 19 questions, the rest only need answers
1 （-8）+（-9）=?
2 （-17）+21=?
3 （-12）+25=?
4 45+（-23）
5 （-45）+23
6 （-29）+（-31）
7 （-390）+（-45）
8 （-28）+37
9 34+（-97）
10 （+3.5）+(-8.5）
11 （-12）+（-13）
12 （-9）+22
13 five and one-quarter + (negative three and one-half) results retain false scores
14 （-2.3）+7
15 (minus four fifths) + (five fifths) results retain false scores
16 （+2.7）+（-3.8）
17 4.23+（-6.77）
18 （-9.18）+6.18
19 （-25）+56+（-39）
20 （-17）+（-14）
Except for the 19 questions, all you need are the answers,

1.-17;
2.4;
3.13;
4.22;
5.-22;
6.-60;
7.-435;
8.9;
9.-63;
10.5;
11.-25;
12.13;
13. One and three fourths;
14.4.7;
15. 13 / 15;
16.-1.1;
17.-2.54;
18.-3;
19. Below;
20.-31;
19.（-25）+56+（-39）=-25+56-39=-8;

How to work out this problem

5/6-7/12=10/12-7/12=3/12=1/4
9/20-11/30=27/60-22/60=5/60=1/12
13/42-15/56=52/168-45/168=7/168=1/24
7/72-19/90=35/360-76/360=-41/360

1. There are the following activities for purchasing books: 10% off for 1-19 copies; 70% off for more than 20 copies (including 20 copies) and 5% off for each
At present, people buy 30 books twice at a total cost of 129 yuan. How many books do they buy each time
2. A batch of existing coal is transported from Xuzhou to Zhenjiang and transported by railway. If 60 tons of coal are loaded in each car, three more cars are needed to transport all the coal; if 225 tons of other materials are loaded in each car, how many tons of coal and how many cars are there
3. There are two rectangles, the length and width of the first rectangle is 1 longer than that of the second rectangle, the length of both rectangles is 1 longer than that of the width, and the perimeter of the first rectangle is 4 larger than that of the second rectangle. Calculate the area of these two rectangles

My homework is the same as yours. These three questions are all wrong. The only one that can be solved is the first one. Those two students are all wrong. It's impossible to buy 6 copies at the first time, because the X * 5 * 0.7 you set means that you bought 20 or more copies at the first time, but you only bought 6 copies at the first time, which is impossible

The number of students in the lower grade of Experimental Primary School accounts for three tenths of the total number of students in the school, 20 less than that in the middle grade, and 300 in the higher grade. How many students are there in the whole grade?

From the meaning of the question: the middle grade students account for more than three tenth of the total number of 20 people
So the whole grade has: (300 + 20) / (1-3 / 10-3 / 10) = 800