(1+1/3+1/5+1/10+1/15+1/30)/(1/2+1/4+1/6+1/12+1/20+1/60)=​? Simple calculation

(1+1/3+1/5+1/10+1/15+1/30)/(1/2+1/4+1/6+1/12+1/20+1/60)=​? Simple calculation

(1+1/3+1/5+1/10+1/15+1/30)/(1/2+1/4+1/6+1/12+1/20+1/60)=(30/30+10/30+6/30+3/30+2/30+1/30)/(30/60+15/60+10/60+5/60+3/60+1/60)=(52/30)/(64/60)=(26/15)/(16/15)=26/15×15/16=13/8

(1 4 / 5-2 5 / 6 + 3 7 / 10-4 8 / 15) / (- 1 / 30)

(1,24 / 30-2,25 / 30 + 3,21 / 30-4,16 / 30) * (- 30)
=(1-2 + 3-4) and (24 / 30-25 / 30 + 21 / 30-16 / 30) * (- 30)
=(- 2) and (4 / 30) * (- 30)
=8

There is such a group of numbers: (1,5,10,), (2,10,20), (3,15,30)... What is the law of this group of numbers? Among them, the sum of the three numbers in group 2005

(1,5,10,), (2,10,20), (3,15,30)... This group of numbers has the rule of (n, 5N, 10N). Among them, the sum of the three numbers in group 2005 is 2005 + 2005 × 5 + 2005 × 10 = 32080

The distance between station a and station B is 330 km. The two trains run in opposite directions at the same time. After 2.5 hours, they meet. The local train runs 60 km per hour, and the express train runs how many km per hour? (solution of a series of equations)

Let the express train run x kilometers per hour. From the meaning of the question, we can get (60 + x) × 2.5 = 330, & nbsp; & nbsp; & nbsp; & nbsp; 150 + 2.5x = 330, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 2.5x = 180, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 72. A: the express train runs 72 kilometers per hour

Solve the unknown binary linear equation!
1、y2-kx2=kx1+2b-y1
2、k((y2-y1)(x2-x1))
Express X2, Y2 with the relation of K, B, x1, Y1
2、k((y2-y1)(x2-x1))=-1

Solvable, the result is very complex, seemingly with a straight line, chord length related equations
The second equation looks like k × (y2-1) / (x2-1) = - 1

When x = 1, the value of the algebraic expression AX2 + BX + 1 is 3, then the value of (a + B-1) (1-a-b) is ()
A. 1B. -1C. 2D. -2

From the meaning of the question: a + B + 1 = 3, we can get a + B = 2, substitute a + B = 2 to get 1 (1-2) = - 1, so choose B

Let u = {- 1,0,1,2} and a = {x ∈ u | x ^ 2 + MX = 0}. If the complement of a = {- 1,2}, then M =? (concrete process)

x²＋mx=0
=>x(x＋m)=0
X = 0 or x = - M
∴A={x∈U|x²＋mx=0}={0,－m}
The complement of a = {- 1,2}
(after removing the elements in a from the complete set u, there are - 1 and 2 elements left.)
∴A={0,1}
The same set contains equal elements
∴－m=1
That is, M = - 1

Let f (x) 2x + x 1 / 2 (x

Since f (x) is an odd function, we consider the function when x > 0
According to the basic inequality, 2x + 1 / X ≥ 2 √ 2, if and only if x = √ 2 / 2, the minimum value is 2 √ 2
①0

If the vertex of the parabola y = x2 + 2mx + (m2-m + 1) is in the third quadrant, then the range of M is ()
A. m＜0B. m＞0C. 0＜m＜1D. m＞1

According to the meaning of the question, − 2M2 ＜ 04m2 − 4m + 4 − 4m24 × 1 ＜ 0, solve the inequality (1), get m > 0, solve the inequality (2), get m > 1; therefore, the solution set of the inequality system is m > 1

The rational numbers a, B and C are not zero. Let x = │ A / (B + C) + B / (c + a) + C / (a + b) │ try to find the power of X19 + 99x + 2000

A, B, C is not zero, and a + B + C = 0, a + B + C = 0, a + B + B + C = 0, a + B + B + C = a, a + B, a + B + B + C = a, a + B + B + B + C = a, a + B + B + C = 0, a, B, a + B + B + C = 0, a + B + B + C = 0, a + B + B + C = 0, a + B + B + B + B = -c, a, a, a + B + B = -c, B, B + B = - A, B, B + B + ||||/ / / (- B + / (- b) + |||\124;||\|/ / / / / (- B + (- B + (- B + / (- B + / (- b(- a) + | B | / (- b) - C / (- C) |