If A1, A2, A3 and A4 are used to represent the number of triangles of 1-4, if A1 = 3, A2 = 8, A3 = 15 What is the relationship between A10 and A9 () This question is to fill in the blanks

If A1, A2, A3 and A4 are used to represent the number of triangles of 1-4, if A1 = 3, A2 = 8, A3 = 15 What is the relationship between A10 and A9 () This question is to fill in the blanks

a10-a9=21
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A commodity is priced at 150% of the purchase price of 100 yuan. The salesperson is allowed to sell the commodity at a discount when the profit margin is not less than 20%. How much discount can the salesperson sell the commodity?

If the profit is not less than 20%, the lowest price can be set as X
（x-100）/100=20%
X = 120 of the solution
So the lowest discount is 120 / 150 = 80%
The minimum discount is 20%

Everyone speed to help me do the first day mathematics fill in the blanks
When an object falls freely, the relationship between the distance h (m) and the time t (s) can be described by the quadratic formula H = 5 * t. built in 1998, Shanghai Jinmao Tower is 420.5 meters high, ranking the third tallest building in the world at that time. If an object falls from a 340 meter high sightseeing hall, it will take about () seconds (accurate to 1 second) to fall to the ground freely
I'm very tired. Speed up

8 seconds

After two price adjustments (one price reduction and one price increase), the price of a commodity is restored. If the first price reduction is 20%, then the second price increase ()
Such as the title

20%/(1-20%)=25%
Second price increase (25%)

A shopping mall reduced the price of a commodity from 40 yuan to 32.4 yuan after two price adjustments
2) According to the survey, if the price of the commodity is reduced by 0.2 yuan, 10 more pieces can be sold. If the commodity can sell 500 pieces per month, how many pieces can be sold per month after two price reductions?
Solving quadratic equation with one variable

store sells the price of a product from two yuan per 40 yuan to 32.4 yuan per item.
(1) If the price reduction rate of the store is the same after two price adjustments, calculate the price reduction rate;
40*(1-x)^2=32.4
x=10%
That is, the price reduction rate is 10%
(2) According to the investigation, 10 more pieces can be sold for every 0.2 yuan price reduction. If 500 pieces can be sold every month, how many pieces can be sold every month after two price adjustments
Total price reduction: 40-32.4 = 7.6 yuan
Saleable: 500 + 7.6 / 0.2 * 10 = 880 pieces

If the original price of a commodity is a yuan, first increase the price by 30%, then reduce the price by 30%, then the final price is expressed in algebraic formula

a*1.3*0.7=0.91a

Algebraic expression: the price of a certain type of car after 10% price reduction is a yuan / car, what is the price before price reduction?

x-1/10x=a
a=9/10x
x=10/9a
10/9a

Sales question: a shopping mall will increase the price of a yuan goods by 40% and then sell them by 60% of the selling price due to overstocking. It uses algebraic expression to express the actual selling price. Is it a loss or a profit this time?

The actual selling price = a × (1 + 40%) × 60% = 0.84a, 0.84a < A, loss

4. The original price of a commodity is 1000 yuan. After the price is increased by 20%, the price will be reduced by 20%. The current price is ()
A. 1000 yuan B. 1040 yuan C. 960 yuan

1000 × (1 + 20%) × (1-20%), = 1000 × 120% × 80%, = 1200 × 80%, = 960 yuan; answer: the current price is 960 yuan

A product is 20 yuan cheaper than the original price after 10% price reduction

Original price: 20 △ 10% = 200 yuan
Current price: 200-20 = 180 yuan
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