The first order equation of one variable, The two ports of AB are 300 km apart. If ship a goes downstream from a to B, and ship B goes from B to a at the same time, the two ships meet at C. If ship B goes downstream from a to B, and ship a goes from B to a at the same time, the two ships meet at D. It is known that the distance between two places of CD is 30 km, and the speed of ship a is 27 km / h,

The first order equation of one variable, The two ports of AB are 300 km apart. If ship a goes downstream from a to B, and ship B goes from B to a at the same time, the two ships meet at C. If ship B goes downstream from a to B, and ship a goes from B to a at the same time, the two ships meet at D. It is known that the distance between two places of CD is 30 km, and the speed of ship a is 27 km / h,

The total time for two people is the same
So CD is the gap between them during this period
So: (x + y) t = 300, (X-Y) t = 30, y = 27
The solution is x = 33
So B's speed is 33 km / h

The travel problem of first order equation with one variable,
A, B and C have three people. A travels 30 meters per minute, B 40 meters per minute and C 50 meters per minute. If a, B and C are in the West Village and C in the East Village, the three of them start from the two villages at the same time. After meeting B, C walks for another 10 minutes before meeting A. how many meters is the distance between the two villages?

Let C meet B in X minutes
40x+50X=30(x+10)+50(x+10)
The solution is x = 80
So the distance between the two villages: 40x + 50x = 7200 (m)

It is known that parabola, hyperbola and ellipse all pass through point m (1,2). They have a common focus on x-axis. The axis of symmetry of ellipse and hyperbola is coordinate axis
Find the equation of three curves

Let the equation of parabola be y ^ 2 = 2px, according to the known 2 ^ 2 = 2p * 1, so the focus coordinate of P = 2 parabola is (1,0), let the equation of ellipse be x ^ 2 / A ^ 2 + y ^ 2 / b ^ 2 = 1, then there is a ^ 2-B ^ 2 = C ^ 2 = 1, (1) and the ellipse passes through the point m (1,2), so 1 / A ^ 2 + 4 / b ^ 2 = 1 (2) solution (1) (2) the system of equations composed of two equations is a = root

3/8X+(1-3/8)X×2/3+55=(1+1/4)X

3/8X+(1-3/8)X×2/3+55=(1+1/4)X
9/24X+(5/8*2/3)X+55=(5/4)X
(9/24)X+(10/24)X+55=(30/24)X
(30/24)X-(9/24)X-(10/24)X=55
(11/24)X=55
X=120

The method of finding the symmetry axis of inverse proportion function
How to find the axis of symmetry of inverse proportion function?

Use the translation method of vector
You have to remember a few basic images, such as
Sin (x); xy = 1; y ^ 2 = 2px, etc
Let's move back
Y = f (x) is translated according to (m, n)
Y-n = f (x-m)

Find the surface of revolution equation 3x ^ 2 + 2Y ^ 2 = 12 and z = 0, rotate one circle around the Y axis
Rotation around which axis, which variable in the equation will remain unchanged, and the other variable will be replaced by the sum of the squares of the remaining two variables, and then square, plus plus or minus sign before the root. Sqrt (x) means square root of X. This seems not to work, the answer in the reference book is 3 (x ^ 2 + Z ^ 2) + 2Y ^ 2 = 12

The other variable is replaced by the sum of the squares of the remaining two variables
Is not x replaced by ± √ (X & # 178; + Z & # 178;)
X & # 178; is not equal to X & # 178; + Z & # 178
No problem

The order and method of fractional mixed operation______ &It's the same

The order of fractional mixing operation is the same as that of integer mixing operation

The expression for finding the minimum value g (a) of the function f (x) = the square of X + ax-3 (1 is less than or equal to x, less than or equal to 3)

f(x)=x^+ax-3 (1≤x≤3)
The opening of the function is upward, and the axis of symmetry x = - A / 2
When - A / 2 ≥ 3, i.e. a ≤ - 6, monotonically decreasing:
Minimum g (a) = f (3) = 3 ^ 2 + 3a-3 = 3A + 6
When 1 ＜ - A / 2 ＜ 3, i.e. - 6 ＜ a ＜ - 2, the extreme value is the minimum value
g(a)=fmin=C-B^2/(4A)=-a^2/4-3
When - A / 2 ≤ 1, i.e. a ≥ - 2, it increases monotonically
Minimum g (a) = f (1) = 1 ^ 2 + A-3 = A-2

Given that X and y satisfy the constraint conditions x > = 0, Y > = 0, 3x + 4Y > = 4, what is the minimum value of the square of X + the square of Y + 2x

From the known 3x + 4Y ≥ 4, so 3x / 4 + y ≥ 1, that is, y ≥ 1-3x / 4, substitute the original formula ≥ x ^ 2 + (1-3x / 4) ^ 2 + 2x = x ^ 2 + 1 + 9x ^ 2 / 16-3x / 2 + 2x = x ^ 2 + X / 2 + 9x ^ 2 / 16 + 1 = 25X ^ 2 / 9 + X / 2 + 1 = (5x / 3 + 3 / 10) ^ 2 + 91 / 100, when x = 0, the original formula has the minimum value (3 / 10) ^ 2 + 91 / 100 = 1

To solve the quadratic equation with one variable,
Square of X + 16x-1161 = 0
X（X+16）=1161
2X（15+2X）+2X20X=246

x²+16x-1161=0
(x+43)(x-27)=0
X = - 43 or x = 27
x(x+16)=1161
x²+16x-1161=0
(x+43)(x-27)=0
X = - 43 or x = 27
The last question is not clear, please ask again,