(1) The length of a train is 300cm. If someone goes in the same direction as the train, the whole train passes the person after 18S. If the person goes in opposite direction to the train, the whole train passes the person after 15s. Find the speed of the person and the train (2) A school organized students to go camping in the nature reserve by car. First, they took a flat road at the speed of 60km / h, then they climbed the slope at the speed of 30km / h, sharing 6.5h. When they returned, they went downhill at the speed of 40km / h, and then took a flat road at the speed of 50km / h, sharing 6h. How far is the nature reserve in the school? (3) The distance between a and B is 36km. Xiaoming rides a bicycle from a to B, and Xiaoli rides a bicycle from B to A. they start at the same time and walk in opposite directions. After one hour, they meet. After another 0.5h, the rest of Xiaoming's journey is twice that of Xiaoli's?

(1) Suppose the speed of the person is XM / s and the speed of the train is YM / s, then 18 (Y -- x) = 3 15 (y + x) = 3 (2) suppose the distance between the school and the nature reserve is (x + y) km, X / 60 + y / 30 = 6.5

Xiao Liang and Xiao Qiang solve equations at the same time
Xiaoliang and Xiaoqiang solve the equations {4x - by = - 2 ax + 5Y = 25} at the same time. Xiaoliang mistook a to get x = - 3 y = - 1. Xiaoqiang mistook B to get x = 5 y = 4
What is the solution of the original equations if calculated correctly?
The answer is correct and clear]

X = - 3, y = - 1 is substituted into 4x - by = - 2 to get b = 10
Then, we calculate a = 1 from x = 5, y = 4 generations ax + 5Y = 25
Then, 4x - by = - 2 ax + 5Y = 25 of generation a and B is solved as 4x - 10Y = - 2 x + 5Y = 25
X=8 Y=17/5

20 simple arithmetical problems in the system of equations of degree 1 with 2 variables in the first day of junior high school

x+y=10,2x+y=13；4x+y=10,2x+y=6；x+y=0,2x+y=13；x+y=125,2x+y=100；x=1,2x+y=3；y=10,2x+y=23；x+y=10,7x+6y=13；3x+y=10,x+4y=55；3x+13y=180,x+4y=-5；x+18y=10,3x+4y=65；3x+y+11=0,7x+4y=4；5x+y=0,11x+4y=55...

If the square y2n-1 of - 2x is a binomial of degree seven, then the value of n is?

2+2n-1=7
2n=6
n=3

There are? Monomials in the formula 2x, 1 / y, 2 square of a - B, 1, 2 square of X + 2 square / 2 of Y

2X, a, square, - B, yes, the rest are not. 3
An algebraic expression without plus minus sign (the algebraic expression of the product of number and letter), a single number or letter is also called a monomial
The product of numbers or letters is called a monomial
The number factor in a monomial is called the coefficient of the monomial. The sum of the exponents of all letters is called the number of times of the monomial
The zero power of any nonzero number is equal to one
There are also unknowns in the fraction. The fraction whose denominator is not unknowns is monomial
Note: 1. The algebraic expression in the form of the product of any letter and number (in division, dividing by a number is equal to multiplying the reciprocal of the number)
2. A letter or number is also called a monomial
3. There is no letter in the denominator
a. - 5,1 x, 2 XY, X / 2 are all monomials, but 0.5 m + n is not

Monomials: X squared, - 2x squared, 3x squared, - 4x squared Find the sum of the first 2011 monomials, and calculate when x = - 1 / 2

Sum of the first 2011 monomials
=（1-2+3-4+5····-2010+2011）x²
=[(1-2)+(3-4)+(5-6)+···+(2009-2010)+2011]x²
=(-1×2010÷2+2011)x²
=(2011-1005)x²
=1006x²
When x = - 1 / 2
=503/2

It is known that (A-1) x2ya + 1 is a quintic monomial of X and Y. try to find the value of the following algebraic formula: (1) A2 + 2A + 1 (2) (a + 1) 2 (3) from the result of (1) (2). What do you think

∵ (A-1) x2ya + 1 is a quintic monomial about X and y, ∵ A-1 ≠ 0, a + 1 = 3, that is, a = 2. (1) when a = 2, A2 + 2A + 1, = 22 + 2 × 2 + 1, = 4 + 4 + 1, = 9. (2) when a = 2, (a + 1) 2, = (2 + 1) 2, = 9. (3) from (1) (2), we find that A2 + 2A + 1 = (a + 1) 2

If the m square of - m x and the n square of Y is a cubic monomial with respect to XY, then M + n=

If the m-th power of - m x and the n-th power of Y are cubic monomials with respect to XY,
Then M + n = 3

If the square of (m-1), the square of X and the N-1 square of Y are quintic monomials of X and y, then what conditions do m and N satisfy?

On the quintic monomials of X and y, then the sum of the degree of X and Y is 5
2+n-1=5
n=4
And the coefficient M-1 ≠ 0
So m ≠ 1, n = 4

Is the sentence "the quadratic power of 3 / N is a binomial"?

It's wrong
Monomials or polynomials belong to the contents of integers. That is to say, monomials or polynomials should at least be integers. The one you give is a fraction, not a monomial