75 times 5 / 74

75 times 5 / 74

=(74+1)×5/74
=74×5/74+1×5/74
=5+5/74
=5 and 5 / 74

What's 50 times 75

50*75=3750

9 times 3 / 5 equals

3/5*9=27/5
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The first formula: 1 + 3 = {4}; the second formula: 1 + 3 + 5 = {9}
The third formula: 1 + 3 + 5 + 7 = {15}; the fourth formula: 1 + 3 + 5 + 7 + 9 = {22}
1. Carefully observe the above operation and results, what rules will you find? Can you write the nth formula?
2. You can write 1 + 3 + 5 + 7 + 9 + quickly +How much is 2003?
1. If a + 1 + (b-2) [index: 2] = 0, find the value of (a + b) [index: 2009] + a [index: 2008]
Because I can't play index, so I use words to express it

1 + 3 + 5 + 7 = {15}, the result should be 16, right?
The fourth formula: 1 + 3 + 5 + 7 + 9 = {22}, the result should be 25, right?
If it is
So the rule is that the result of the first formula is (1 + 1) ^ 2 = 4
The result of the second formula is (2 + 1) ^ 2 = 9
The result of the third formula is (3 + 1) ^ 2 = 16
The result of the fourth formula is (4 + 1) ^ 2 = 25
The result of the nth formula is (n + 1) ^ 2
The size of the last number of each formula is equal to 2n + 1
(for example, the last number of the first formula is 3, satisfying 3 = 2x1 + 1, the last number of the second formula is 5, satisfying 5 = 2x2 + 1, and so on.)
So 1 + 3 + 5 + 7 + 9 + +In 2003
2003 is in the above formula corresponding to 2n + 1 = 2003, n = 1001
1+3+5+7+9+…… +2003=1001^2=1002001
2,
A + 1 + (b-2) [index: 2] = 0
Because a + 1, (b-2) ^ 2 is greater than or equal to zero,
So a + 1 = 0, a = - 1
（b-2）^2=0,b=2
(a + b) [index: 2009] + a [index: 2008]
=（-1+2）^2009+(-1)^2008
=1+1
=2

1. If XY ≠ 1 and 7x ^ 2 + 2009x + 13 = 0 and 13y ^ 2 + 2009y + 7 = 0, then the value of X / y is ()
A.13/7
B.7/13
C.-2009/7
D.-2009/13
2. If 3-digit ABC (representing 3-digit of 100 digit a, 10 digit B and one digit C) satisfies B

1. X = (- 2009 + a) / 14, y = = (- 2009 + a) / 26, so x / y = 13 / 7
Because multiple choice questions can guarantee the correct rate, this method is not good, but other did not come up with
2. The molecule is c1,9 * c1,9 + c1,8 * c1,8 +... + C1,1 * C1,1 = 285
If the middle number is 0, both sides can choose from 1 to 9, there are 9 * 9... If the middle number is 8, both sides can only be 9
Nine in the middle is impossible
The denominator is c1,9 * c1,10 * c1,10 = 900, and all three digits have 900
So the answer is 285 / 900 = 19 / 60

A two digit number is the square of a one digit number. The three digit number formed by placing the one digit number on the left side of the two digit number is 252 larger than the three digit number formed by placing the one digit number on the right side of the two digit number
Someone uses a 7.5-meter-long wall as one side and a 13 meter long fence as the other three sides to form a rectangular vegetable garden with an area of 20 square meters. What is the length and width of the rectangular vegetable garden?
A green belt with the same width is set around the rectangular site with a length of 40 meters and a width of 30 meters, so that the remaining area is half of the original area. What is the width of the green belt?

The first question: according to the meaning of the question, only these two digits are qualified: 16 (the square of 4), 25 (the square of 5), 36 (the square of 6), 49 (the square of 7), 64 (the square of 8), 81 (the square of 9). Then, try one by one Finally found that 16, 49 meet the conditions, so that the two

After the Wenchuan earthquake, an enterprise in our city donated 600 tents of a and B with a value of 940000 yuan to the disaster area. It is known that each tent of a is 1700 yuan, and each tent of B is 1300 yuan. How many tents are there?

940000 = 940000, (1700 × 600-940000) △ 1700-1300, = 80000 △ 400, = 200 (top), so a tent has: 600-200 = 400 (top), answer: a tent has 400, B tent has 200

A junior high school mathematics problem, solution process and answer. Speed
It is known that the univariate quadratic equation 1 / 2x ^ 2-x = a (x-1) + 1 = 0 has two real roots x1, X2, if y = X1 + x2 + x1x2
When a ≤ - 2, compare the size of Y and - A ^ 2 + 10a-15 and explain the reason

1 / 2x ^ 2-x = a (x-1) + 1 = 0
It should be 1 / 2x ^ 2-x-a (x-1) + 1 = 0
x²/2-(a+1)x+a+1=0
There are: X1 + x2 = 2 (a + 1)
x1x2=2(a+1)
If y = X1 + x2 + x1x2 = 4 (a + 1)
When a ≤ - 2,
-a²+10a-15-y
=-a²+10a-15-4(a+1)=-(a²-6a+9)-10=-(a-3)²-10-a²+10a-15

Can solve a few solutions, with junior high school methods on the line
1. When Xiaoqian and Xiaodong do math problems, they get 20 points for each correct one and 12 points for each wrong one. They do 10 for each and get 208 points in total. Xiaoqian has 64 points more than Xiaodong. How many problems do they do right?
2. The original rectangular green space is reduced by 2m in length and increased by 2m in width. After the transformation, a square green space is obtained. Its area is twice that of the original green space. The square area after the transformation can be calculated
3. A rooster is worth 5 yuan, a hen is worth 3 yuan, and three chickens are worth 1 yuan. How many roosters, hens and chicks do you buy with 100 yuan?
4. When someone is on a short journey, the hour hand and minute hand of the clock coincide between 8:00 and 9:00 a.m. and arrive at 180 ° between 2:00 and 3:00 p.m. to calculate the travel time
5. When a kindergarten goes to the library to borrow books, if it borrows 35 books, it will be sent to each child with an average difference of 1. If it borrows 56 books, it will be sent to each child with an average difference of 2. If it borrows 69 books, it will be sent to each child with an average difference of 3. How many children are there at most?

In the first problem, let Xiaoqian and Xiaodong do X and Y problems respectively, then 20x + 20y-12 (10-x) - 12 (10-y) = 20820x-12 (10-x) = 20y-12 (10-y) + 64. By solving the equations, we get x = 8y = 6, Xiaoqian does 8 problems and Xiaodong does 6 problems. In the second problem, if the side length of the square is XM, then x & # 178; = 2 (X-2) (x + 2) x & # 178; = 8, then the square after transformation

Observe the following figures:
★ ★ ★
★ ★ ★ ★ ★ ★
★ ★ ★ ★ ★ ★ ★ ★ ★
★★★ ★★★ ★ ★ ★ ★ ★ ★
★ ★ ★ ★
① ② ③ ④
They are arranged according to a certain rule. According to this rule, how many are there in the ninth figure?

The first is four
Add three to the second one
Third, add three more
So the ninth has 4 + 3x8 = 28
The rule is: 3N + 1
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