The product of 1997 times 0.3 divided by 1999 times 0.5 plus the product of 1.2 divided by 1999 is calculated by a simple method

The product of 1997 times 0.3 divided by 1999 times 0.5 plus the product of 1.2 divided by 1999 is calculated by a simple method

I wrote it on my mobile phone, but I can't understand it in some places. Let's make do with it. 1997 * 0.3 / 1999 * 0.5 1.2 * 0.5 / 1999 * 0.5 = 1997 * 0.3 / 1999 * 0.5 0.3 * 4 * 0.5 / 1999 * 0.5 = 1997 * 0.3 / 1999 * 0.5 2 * 0.3 / 1999 * 0.5 = (1997 + 2) * 0.3 / 1999 * 0.5 = 3 / 5

If the intersection points of the image of quadratic function y = x ^ 2 + (M-3) x + m and X axis are on both sides of point (1,0), then the value range of M is

If the discriminant of root is greater than 0, M is greater than 9 or less than 1
When x = 1, y must be less than 0, so m is less than 2
So m is less than 1

According to the law of constant quotient, fill in the appropriate number in the brackets. 234 divided by () = 26. () divided by 3 = 26. () divided by 6 = 26.312 divided by () = 26.312
I'll be K's. have pity on me~

234 divided by (9) = 26
(78) divided by 3 = 26
(156) divided by 6 = 26
312 divided by (12) = 26

A cuboid wooden box with a cover, the volume is 0.576 cubic meters, its length is 12 decimeters, width is 8 decimeters, to make such a wooden box at least use wood how many square meters?

12 decimeters = 1.2 meters, 8 decimeters = 0.8 meters, 0.576 ^ (1.2 × 0.8), = 0.576 ^ 0.96, = 0.6 (meters); (1.2 × 0.8 + 1.2 × 0.6 + 0.8 × 0.6) × 2, = (0.96 + 0.72 + 0.48) × 2, = 2.16 × 2, = 4.32 (square meters); answer: the wooden box needs at least 4.32 square meters

If a three digit number is divided by 37, the remainder is 17, divided by 36, and the remainder is 3, then the three digit number is 3______ ．

Let the quotient of a three digit number divided by 37 and the remaining 17 be a, then the three digit number can be written as: 37 × a + 17 = (36 + 1) × a + 17 = 36 × a + (a + 17). Because "divide by the remaining 3", so (a + 17) divided by 36 needs the remaining 3, and the quotient can only be 22. Therefore, the three digit number is 37 × 22 + 17 = 831

Find sequence 1,1-3,1-3 + 9,1-3 + 9-27 The sum of the first n terms

An = (- 3) ^ 0 + (- 3) ^ 1 + (- 3) ^ 2 +... + (- 3) ^ (n-1) = (1 / 4) [1 - (- 3) ^ n] sequence 1,1-3,1-3 + 9,1-3 + 9-27 The sum of the first n terms = a1 + A2 +... + an = (1 / 4) {n - (- 3) [1 - (- 3) ^ n] / 4} = (1 / 4) [n + (3 / 4) (1 - (- 3) ^ n)]

40 divided by 50 equals (): 40

40÷50×40
=32
40 divided by 50 equals (32): 40

The square of the solution of the equation (x + m) about x = n

Square of (x + m) = n
When n < 0, the original equation has no real solution
When n ≥ 0, x + M = ± √ n
x=-m±√n

30 divided by 16 equals - a few quarters equals nine quarters equals 0.75

30/16=15/8=7.5/4=9/4.8
It can't be equal to 0.75

When a is an integer, the solution X and y of the system x + Y-A = 0.5x + 3Y = 31 are positive integers

From 5x + 3Y = 31. X + Y-A = 0, 2x = 31-3a, x = (31-3a) / 2 is a positive integer, 2Y = 5a-31, y = (5a-31) / 2 is a positive integer, so 31-2a ≥ 2, 5a-31 ≥ 2, solution a ≤ 29 / 2, a ≥ 33 / 5, so a = 7,8,9,10,11,12,13,14, and because X and y are positive integers, so a = 7,9, x + y = a (1) 5x + 3Y = 31 (2) (2)