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What is the value of m.n? (x ^ 2 + MX + 3) (x ^ 2-3x + n) does not contain x ^ 2 and x ^ 3?
(x^2+mx+3)(x^2-3x+n)
=x^4-3x^3+nx^2+mx^3-3mx^2+mnx+3x^2-9x+3n
=x^4+(m-3)x^3+(n-3m+3)x^2+(mn-9)+3n
If the above formula does not contain x ^ 2 and x ^ 3 terms, you must
M-3 = 0 and n-3m + 3 = 0
So: M = 3, n = 6
A: when m = 3, n = 6, the original formula does not contain x ^ 2 and x ^ 3 terms
Is zero a natural number? Since zero can represent both positive and negative integers, why does natural number not include negative integers?
0 is a natural number
0 cannot represent a positive integer or a negative integer
0 is 0, which is neither a positive integer nor a negative integer
Natural numbers refer to non negative integers, including positive integers and 0
Now there are 42 Chinese books, 112 mathematics books and 70 natural numbers. They are divided into several piles on average. The number of these three books in each pile is the same. 1
How many piles? 2. How many Chinese books are there in each pile? 3. How many math books are there in each pile? 4. How many nature books are there in each pile?
There must be a formula
1. If the greatest common divisor is 14, it can be divided into 14 piles,
2. Each pile of Chinese books has 42 / 14 = 3
3. Each pile of math books has 112 / 14 = 8
3. 70 / 14 of each stack of nature books = 5
Party A and Party B start from AB and face each other. Party A walks 3 kilometers per hour and Party B walks 2 kilometers per hour. When they meet, they are 3 kilometers away from the midpoint. How many kilometers is the distance between the two points
30km 3-2 = 1km 3x2 = 6km 6 △ 1 = 6h (3 + 2) X6 = 30km
Calculation: (1 + 2) (1 + 2 ^ 2) (1 + 2 ^ 4) (1 + 2 ^ 8) (1 + 2 ^ 16) (1 + 2 ^ 32) (1 + 2 ^ 64)
（1+2）（1+2^2）（1+2^4）（1+2^8）（1+2^16)（1+2^32）（1+2^64）=(2-1)（1+2）（1+2^2）（1+2^4）（1+2^8）（1+2^16)（1+2^32）（1+2^64）=(2^2-1)（1+2^2）（1+2^4）（1+2^8）（1+2^16)（1+2^32）（1+2^64）=(2^...
The distance between a and B is 60 kilometers. How many centimeters should the distance be drawn on a map with a scale of 1:3000000?
60 km = 60 000 00 cm
60 000 00 △ 30 000 00 = 2 cm
A: the distance between the two places should be 2 cm
Let C lie in the closed region (including the boundary) enclosed by the parabola y2 = 2x and the straight line x = 3, then the maximum value of the radius of the circle is ()
A. 32B. 4-6C. 4+6D. 6-1
When the radius of circle C is the maximum, we know from the symmetry that the center of circle C should be in the interval (0, 3) on the x-axis, and the circle C is tangent to the straight line x = 3. Suppose that the center of circle C is (a, 0) (0 < a < 3), then the equation of circle C is (x-a) 2 + y2 = (3-A) 2 ^, where y2 = 2x is substituted, (x-a) 2 + 2x = (3-A) 2 ^, that is, X2 + 2 (1-A) x + 6a-9 = 0, ∵ circle C is tangent to the parabola, and the discriminant is △ = [2 (1-A) ）]2-4 (6a-9) = 0, ∫ 1-A) 2-6a + 9 = 0, ∫ a2-8a + 10 = 0, ∫ 0 < a < 3 ∫ a = 4-6, ∫ the maximum radius of circle C is 3-A = 3 - (4-6) = 6-1
Party A and Party B have several books in total. It is known that the ratio of Party A to the total number of books is 3:7. If Party B gives Party A 15 books, the number of books of both parties is equal. How many books did Party A and Party B have?
The total number of books: 15 △ 12-37, = 15 △ 114, = 210 (Books); a: 210 × 37 = 90 (Books); B: 210-90 = 120 (Books); answer: a originally had 90 books, B had 120
A real estate development company bought a piece of land with 1 million yuan. The land can build a building of 1000 square meters per floor. The average construction cost per square meter of the building is related to the building height. The construction cost of the whole building will be increased by 20 yuan per square meter when the building rises by one floor. It is known that the construction cost per square meter of a five floor building is 400 yuan The cost is the lowest (the comprehensive cost is the sum of the construction cost and the land purchase cost), and the company should build the floor______ Layer
Let's build an x-floor building. According to the meaning of the title, the land purchase cost per square meter is 1000000 △ 100x = 1000x. Let's set the construction cost of the first floor as a yuan. According to the title, a + (a + 20) + (a + 40) + (a + 60) + (a + 80) 5 = 400, the solution is a = 360, and the construction cost per square meter is 360 + 20 + 40 + 60 + 80 + +20 (x − 1) x = 10x + 350 (yuan), so the average comprehensive cost per square meter is y = 10x + 350 + 1000x ≥ 350 + 210x · 1000x = 350 + 200 = 550. If and only if 10x = 1000x, that is, x = 10, the average comprehensive cost per square meter of the building is the lowest
After a period of time, the two cars meet at a distance of 40 km from the midpoint of the whole journey. The speed ratio of the two cars is 7:5
How many kilometers is the distance between a and B?
Tonight,
The distance between a and B is: (40 + 40) / (7-5) x (7 + 5) = 480 (km)
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