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On the two equations of X, X square-x-2 = 0 and 1 / 2 of X-2 = x + 2 / a have the same solution, then what is a =?
x²-x-2=0
(x-2)(x+1)=0
x=2,x=-1
1/(x-2)=2/(x+a)
X-2 at the denominator, not equal to 0
So x is not equal to 2
So x = - 1
1/(-1-2)=2/(-1+a)
a-1=-6
a=-5
The solution of the equation 3 / x = - 6 / 1 is
Analysis
x/3=-1/6
Both sides at the same time * 3
x=-1/2
Make up a practical problem, make the equation 3x + 4 (45 - x) = 150, and communicate with students
A. B is 150 km apart. The sum of the speed of a and B is 45 km / h. one hour after a starts from a, B starts from B, and three hours later they meet. How many kilometers does B walk per hour?
On a section of double track railway, two trains pass at the same time. The speed of train a is 20 m / s, and that of train B is 24 m / s,
If train a is 180 meters long and train B is 172 meters long, how long will it take for the two trains to miss?
Driving in opposite direction: (180 + 172) / (20 + 24) = 8 (seconds)
Driving in the same direction: (180 + 172) / (24 - 20) = 88 (seconds)
If the average of 1,2,3, X is 5, and the average of 1,2,3, x, y is 6, then the value of Y is
10
A and B both ride from two places at the same time. A travels 20 kilometers per hour, B travels 18 kilometers per hour. The distance between the two people is 3
M. how many kilometers is the whole journey?
It is 3km away from the midpoint of the whole journey
Jiaduo walked 3x2 = 6km
Encounter time 6 △ 20-18 = 6 △ 2 = 3 hours
(20 + 18) X3 = 38x3 = 114km
Prove by mathematical induction: 1 ^ 2 + 2 ^ 2 + +N ^ 2 = n (n + 1) (2n + 1) / 6 (n is a positive integer)
When n = 1, left = 1 ^ 2 = 1, right = 1 * (1 + 1) * (2 + 1) / 6 = 1; let n = K be immediate: 1 ^ 2 + 2 ^ 2 + +If K ^ 2 = K (K + 1) (2k + 1) / 6, then 1 ^ 2 + 2 ^ 2 + +k^2+(k+1)^2=k(k+1)(2k+1)/6+(k^2+2k+1)=(2k^3+3k^2+k+6k^2+12k+6)/6=(k+1)(k+2)(2k+3)/6=(k+1)[(k+1)+1...
On a map with a scale of 1:3000000, it is measured that the distance between a and B is 3cm. If a and B are drawn at a scale of 1:2000000, the distance between a and B is 3cm
How long is the distance between a and B on the map?
1: 3000000 / 1:20000000 = 2:3, the distance between a and B should be drawn 3 (2 / 3) = 4.5cm
Finding the minimum value of y = x & sup2; + 2x + 3 in the interval [T, t + 1]
The detailed process needs to be clear:
Finding the minimum value of y = x & sup2; + 2x + 3 in the interval [T, t + 1]
The axis of symmetry of the function: x = - 2A / b = - 1
So there are three situations to discuss
1、t+1
Party A and Party B share several books. It is known that Party A accounts for 3 / 7 of the total number. If Party B gives party a 10 books, the number of books is equal. How many books do Party A and Party B have?
Application problem, it is best to use arithmetic, if it is the hope of equation, the solution process is also written out
10 divided by 1 minus 3 / 7 times 2 gives 70
70 times 3 / 7 = 30
70-30 = 40 (this) --- B
Sorry, I don't know how to type symbols. You can make do with 8!
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