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Check whether the solution of the equation is in the brackets below. [1] 2x-1 = 1 / 2X-4 {x = - 2, x = - 1 / 2} [2] 1 / 2x = 2 / 3x + 2 {x = 12, x = - 12}
【1】2x-1=1/2x-4{x=-2,x=-1/2}
When x = - 2,
Left = 2 * (- 2) - 1 = - 4-1 = - 5,
Right = 1 / 2 * (- 2) - 4 = - 1-4 = - 5,
The left is equal to the right
So x = - 2 is the solution of the equation 2x-1 = 1 / 2X-4
In the same way, it can be determined that x = - 1 / 2 is not the solution of the equation 2x-1 = 1 / 2X-4
2) X = 12 is not the solution of the equation 1 / 2x = 2 / 3x + 2
X = - 12 is the solution of equation 1 / 2x = 2 / 3x + 2
A series of equations in the first year of junior high school solve practical problems
The length of a detachment is 450m, advancing at a speed of 1.5m per second. A messenger sends a message to the head of the platoon and immediately returns to the end of the platoon. His speed is 3M per second
That's what I asked.
Let T1 be the past time, then S1 = 1.5t1
S2+450=3T1
S1 = S2 so 1.5t-3t = - 450 so t = 300
Let T2 be the return time, T2 = s * V1 + V2, so T2 = 450 * 1.5 + 3 = 100
So total T = 100 + 300 = 400 (s)
A few application problems, fast, had better not make equation
1. Xiaoming and Xiaojun set out from a and B at the same time and walk towards each other. If they advance at the original speed, they will meet at 4 o'clock; if they are both 1 km / h faster than the original speed, they will meet at 3 o'clock. How many kilometers are there between a and B?
2. Xiaohong and Xiaoqiang start from home at the same time. Xiaohong walks 52 meters per minute and Xiaoqiang walks 70 meters per minute. They meet at a in the picture. If Xiaohong starts 4 minutes in advance and Xiaoqiang walks 90 meters per minute, they still meet at a. how many meters is the distance between Xiaohong and Xiaoqiang's home?
3. The speed of the sailing boat is 60m / min. in the river with the current speed of 20m / min, it takes 3 hours and 30 minutes for the boat to go from a port in the upstream to a place in the downstream and then return to the original place. How long does it take for the boat to go from the port in the upstream to a place in the downstream?
4. The standard of charging electricity fee in a certain place is: if the monthly electricity consumption does not exceed 50 degrees, charge 50 cents per degree; if it exceeds 50 degrees, charge 8 cents per degree for the part exceeding 50 degrees, and user a pays 3 yuan and 3 cents more than user B each month. How many degrees of electricity did user a and user B use this month?
5. A circle of metal wire is 30 meters long, 3 wires of length a and 5 wires of length B are cut off. If the remaining two wires of length B are cut off again, the difference is 0.4 meters. If the other two wires of length a are cut off again, the difference is 2 meters. How many meters is the length of a?
Expression expression
A company has to deliver two kinds of building materials (A and b) to the construction site. Each kind of building material (a) weighs 700 kg, with a total of 120 pieces, and each kind of building material (b) weighs 900 kg, with a total of 80 pieces. It is known that a car can carry up to 4 tons each time, so how many times does it take for five identical cars to transport at the same time?
1. A: the distance between a and B is 24 km. 1 + 1 = 2 (km / h) 2 * 3 = 6 (km) 6 * 4 = 24 (km) 2. A: Xiaohong and Xiaoqiang are 2196 meters apart. 90 * 4 = 360 (m) 90-70 = 20 (m / min) 360 / 20 = 18 (min) 70 + 52 = 122 (M / min) 122 * 18 = 2196 (m) 3
1. A workshop originally planned to produce 120 parts in X days. Due to the adoption of new technology, it produced 3 less parts per day, so it completed the task two days later. The equation is as follows________________
2. Mr. Zhang and Mr. Li set out from school at the same time and walked 15 kilometers to the county town to buy books. Mr. Zhang walked 1 kilometer more per hour than Mr. Li, and as a result, they arrived half an hour earlier than Mr. Li. Suppose Mr. Li walked x kilometers per hour. According to the problem, we can get the equation as follows____________
3. It takes the same time for Party A to make 90 parts and Party B to make 120 parts, and Party A and Party B make 35 parts in one hour. Let Party A make x parts per hour_____________
4. To build a dam in our city, it needs to be completed within the specified date. If it is done by team a, it can be completed as scheduled. If it is done by team B, it needs to exceed the specified date by 3 days. Now it is done by team a and team B together for 2 days, and the rest of the project is done by team B alone, just within the specified date. If the specified date is x days, the equation can be set as follows______________
5. Li Ming plans to finish a Book of 200 pages within the prescribed time. After five days of reading, he changes his plan and reads five more pages every day. As a result, he finishes reading one day ahead of schedule. Suppose Li Ming originally plans to read x pages every day______________
Give me a clear score
1120 * x = (x + 2) * (120 / x-3) how many column equations to produce in total 120 * x is the total number of production (x + 2) and then the number of days to produce multiplied by (120 / x-3) and then how many column equations (15 / X - 0.5) * (x + 1) = 15 in front of teacher Zhang's time, followed by teacher Zhang's speed
RELATED INFORMATIONS
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