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The solution of inequality M & # 178; X-1 about X
m²x-1
If the inequality (k-1) xk2 + 2 > 13 is a linear inequality of one variable, then K=______ ．
According to the problem meaning K2 = 1 and (k-1) ≠ 0, we get k = ± 1 and K ≠ 1, so k = - 1
The inequality of one variable and one degree in Mathematics
China mobile charges are divided into two categories. Category a charges are as follows: no matter how long the call time is, each mobile phone must pay a monthly rent of 50 yuan per month. In addition, it pays 0.4 yuan per minute of call. Category B charges are as follows: there is no monthly rent, but it charges 0.6 yuan per minute of call. 1. The average call time of a user is 300 minutes per month. Which charging method is more cost-effective?
2. When a user calls for 200 minutes a month, which charging method is more cost-effective? 3. How many minutes a month, according to the A and B charging standards, the payment is equal?
1. When the call time is 300 minutes, scheme A: 50 + 0.4 * 300 = 170 yuan
Scheme B: 0.6 * 300 = 180 yuan, scheme A should be chosen
2. When the call time is 200 minutes, scheme A: 50 + 0.4 * 200 = 130 yuan
Scheme B: 0.6 * 200 = 120 yuan, scheme B should be chosen
3. When the call is set to be X minutes, AB charges the same
Then 50 + 0.4x = 0.6x
0.2x=50
X = 250, that is, when the call is 250 minutes, AB charges the same
On the mathematical problems of linear inequality of one variable
Mo lives in the community and plans to purchase and terminate 400 saplings. A sapling company provides the following information:
Information 1: there are three kinds of saplings to choose from: poplar, clove and willow, and the quantity of poplar and clove should be equal
Information 2: saplings poplar clove willow
The wholesale price of each sapling is 3
After two years, the air purification of each tree seedling was 0.40.10.2
index
=If the total cost of purchasing these three kinds of seedlings is w yuan, and if the sum of the air purification index of the residential area after two years is not less than 90, try to find the value range of W
I write w ≥ 2200, right?
Suppose you buy x poplar trees, then you buy x clove trees and 400-2x willow trees. From the question meaning: 0.4x + 0.1X + 0.2 (400-2x) ≥ 90400-2x ≥ 0, the solution is: 100 ≤ x ≤ 200W = 3x + 2x + 3 (400-2x) = 1200-x, w decreases with the increase of X, and 100 ≤ x ≤ 200, ■ - 200 + 1200 ≤ w ≤ -
RELATED INFORMATIONS
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