An application question on a quadratic equation in the exam

2: Long decrease: (25-5) (60+5) = 1300 (not in accordance with the title to be rounded) so only 1 is correct.

The above step is redundant, it belongs to the drawing of snakes, there is no need, you have already found x=25, that is, the length of your assumption, and the substituting formula will find the length and width after the increase. There is no such thing as X-5 in your hypothesis.

Your assumption is not rigorous, since the title says "one side", you assume that one side is x meters long and the other side is 1500 x meters long, so you can determine which side is long and which side is wide based on the calculation results, otherwise the length you calculate is smaller than the width.

Just do that.

25 + 5 = 30 (m).

60-5 = 55 (m).

After the increase, it is 55 meters long and 30 meters wide.

11 points, you can probably get about 8 points.

I know that it is to find the length and width of the playground after the area is increased.

When I say find out the x-descendants, I mean the x+5 and 1500 x-5 of the playground after the area is increased.

Do you understand what I mean?

This question is not very good. The addition and subtraction in the middle is just a condition for you to calculate the problem, not the real addition and subtraction, and then there is addition and subtraction, how to finally find the length and width of the addition, one of them is not addition or subtraction. I can't ask the right questions. You remember wrong.

If the number of days required for Xiaoqiang to complete alone is x, then it takes x+5 days for Xiao Ming to complete alone, then 1 (1 x+1 (x+5)))=x-5

It takes 2 days for Xiaoqiang to complete the 5+5 root number alone.

In fact, you can not use 1, for example, m is used to represent the total amount.

Since you can make an appointment with 1, it is more convenient.

The 1 here refers to the unit "1", which specifically refers to the total amount of work for this job. So divide by 1, or divide by 1.

If the number of days required for Xiao Qiang to complete alone is a, then Xiao Ming needs a+5 days to complete it alone1 (1 a+1 (a+5)))=a-5

The solution yields a1 = 5-5 times the root number 2 a2 = 5 + 5 times the root number 2 because a is greater than 0, so a = 5 + 5 times the root number 2

Answer: It takes (5+5 times the root number 2) days for Xiaoqiang to complete alone.

(1) Let bc be x and ab be y, where x 15 meters can be a system of equations: x+3y=24

xy=45 gives x=15, y=3 or x=9, y=5, i.e., AB is 3 meters or 5 meters long.

2) Obtained from x+3y=24, y=(24-x) 3, then the flowerbed area = xy=x(24-x) 3= -1 3(x-12) 2+48

Because x 15, the maximum area of the flower bed is when x = 12, the maximum area is 48 square meters, that is, ab = 4 meters, and when BC = 12 meters, the maximum area of the flower bed is 48 square meters.

Because the object falls from a high altitude and is in free fall, so:

1) H = 1 2·g·t 2 (take g =, t = 10 seconds (2) 98 10 =

3) i.e., h=490-140=350, h=1 2·g·t 2 (take g=, t=s.

1. There is a two-digit number, and the sum of the digits in the ten digits and the digits in the single digit is 8. If the number in the tenth digit is reversed with the number in the single digit, the resulting two-digit number is multiplied by the original two-digit number, and 1855 is obtained. Find the original two-digit number.

2. Yiqun boutique buys a batch of goods at 21 yuan per piece, the goods can be priced by themselves, if the price of each product is a yuan, it can be sold (350 10a), but the price bureau limits the profit of each commodity shall not exceed 20%, and the store plans to make a profit of 400 yuan, how many pieces do you need to purchase? How much should each item be priced?

3. Wang Hongmei will deposit 1,000 yuan of New Year's money into the "Children's Bank" for the first time on a regular basis for one year, take out the principal and interest after expiration, and donate 500 yuan to the "Hope Project", and the rest will be deposited regularly for one year, at this time, the annual interest rate of the deposit has been reduced to 90% of the annual interest rate of the first deposit, so that after the maturity, you can get a total of 530 yuan of principal and interest, and ask for the annual interest rate of the first deposit. (assuming no interest tax).

4, a commercial building in September sales of 2 million yuan, October sales fell by 20%, commercial building from November to strengthen management, improve management, so that sales rose steadily, December sales reached 10,000 yuan, the average growth rate of these two months.

2.Solution: According to the meaning of the question, get (A 21) (350 10A) 400, sort, get A2 56A + 775 0, solve this equation, get A1 25, A2 31

Because 21 (1+20%) a2=31 is not in line with the topic, so it is discarded.

So 350 10a 350 10 25 100 (pieces).

A: 100 pieces need to be purchased, and each item should be priced at 25 yuan.

3.The annual interest rate at the time of the first deposit is x

According to the title, [1000(1+x) 500](1+

Finishing, get 90x2+145x3 0

Solve this equation to get x1 , x2

Since the deposit interest rate cannot be negative for Hotaka Yu, x2 will be rounded off.

A: The annual interest rate for the first deposit is approximately.

4.The average growth rate for the two months was x, then according to the meaning of the question, get 200 (1 20%) (1 + x)2 , that is, (1 + x) 2 , solve this equation, get x1 , x2 rounded).

A: The average growth rate for these two months is 10%.

Under the premise of not withdrawing funds and profits (that is, the profits obtained in the first year are also used as production funds), the profit margin of the second year is 8 percent higher than the profit margin of the first year (the profit rate is the ratio of the profit obtained to the production capital to the lead Li Lu) in the first year. If the profit in the second year is $1.12 million, what is the profit margin in the first year?

Renming shopping mall sales in January 2010 for 1 million yuan, sales in February fell by 10%, into March the mall took measures to reform the delivery strategy, so that the monthly sales rose sharply, sales in April reached 10,000 yuan. Find the average growth rate of sales for the month.

Solution: According to the meaning of the topic, it can be seen that the sales in February are: 100 * (1-10%) = 900,000 yuan, and the average growth rate of monthly sales is x, then:

90*（1+x)^2=

1+x)^2=

1+x= 1+x= (rounded).

x = i.e. the average growth rate of monthly sales is 20%.

Solution: Let the bamboo pole be x meters long and the door is at right angles, so there is the following equation:

x+4）²+x+2）²=x²

Set up bamboo poles x feet long; The door is a foot wide; Height b feet.

a + 4 = x ;

b + 2 = x;

a^2 + b^2 = x^2

Solution; a=6, b=8 ; x=10

The bamboo pole is 10 feet long.

This bamboo pole is x feet long.

x-4)²+x-2)²=x²

x²-8x+16+x²-4x+4=x²

x²-12x+20=0

x-2)(x-10)=0

x1=2 (rounded), x2=10

A: The bamboo pole is 10 feet long.

Solution: Set the length of the bamboo pole to A

According to the Pythagorean theorem, a 2 = (a-4) 2 + (a-2) 2

So a=10, a=2 (rounding).

1. Lift the price increase of x yuan.

Lift the price increase of X yuan.

10-8+x）（200-x÷

x-3）（x-5）=0

x1=3 x3=5

10 + 3 = 13 yuan 10 + 5 = 15 yuan.

A: When the price is 13 yuan or 15 yuan, the daily profit is 700 yuan.

2. Lift the price increase of x yuan, and the daily profit is y yuan.

Then: y=(10-8+x)(200-x

Finished: y = -20x +160x+400 when x = -160 (-20 2)=4, y has a maximum value, 720 then when the daily price is 4 + 10 = 14 yuan, the daily profit is the largest, 720 yuan.

Let's say the price rises in yuan.

Profit p=(10-8+.)

1) Let p = 700, solve x = 10, that is, the price increase is 10 *, that is, when the price is 15 yuan, the daily profit is 700 yuan.

2) From equation (a), it can be seen that when x=8, that is, the mobile phone is 10+ yuan, the maximum profit can be obtained, which is 720 yuan.