Xiao Gang, Xiao Li and Xiao Ming each have some pictures. The ratio of the three is 8:5:2. Xiao Li has 30 pictures. How many pictures do Xiao Gang and Xiao Ming have?

Divide 30 by 5 to get 6,
Multiply 6 by 8, and 48 is Xiaogang's,
Finally, multiply 6 by 2, and 12 is Xiaoming's,
Xiao Gang has 48, Xiao Ming has 12

Xiao Cong and Xiao Ming have some glass balls. Xiao Cong says to Xiao Ming, "my glass balls are twice as big as yours." Xiao Ming says to Xiao Cong, "if you give me three, we'll have the same number." how many glass balls do they have?

According to the stem analysis, the number of Xiaoming's glass balls is 3 × 2 = 6, XiaoCong's glass balls is 6 × 2 = 12, a: XiaoCong has 12, Xiaoming has 6

What is the reduction of fractions

That is to reduce the greatest common divisor of numerator and denominator

(2x+3)(2x+1)=(x+1)^2+(x+2)^2+x^2+17+(x-1)^2

2x+3)(2x+1)=(x+1)^2+(x+2)^2+x^2+17+(x-1)^2
4X^2+8X+3=4X^2+4X+23
4X=20
X=5

Do not change the value of the fraction so that the numerator and denominator of the following fractions do not contain symbols
-4x^2/-9y
-a-b/b

4x^2/9y- a/b -1

[(2x-1 / 4 y) (2x + 1 / 4 y) - (2x-1 / 4 y) & # 178;] & # 178;
calculation

One of the (2x-4-4-one-y) (2x + 4-one-y) (2x-4-one-of-4) (2x-4-one-of-4-one-of-4 (one-of-2x-4-one-of-4-one-of-y) (2x-4-one-of-one-of-4-one-of-2x-4-one-of-4-one-of-four-of-one-of-four-of-of-four-half-of-four-one-of-of-four-of-four-of-one-half-of-four-one-half-half-of-four-half-four-of-half-four-one-half-one-half-half-half-four-half-half-half-half-half-half-half-half-half-half-half-4-half-half-half-half-of-half-four-half-half-four-half-half-half-half-half-of-if there is anything in this question

It is proved by line generation that if there is no solution for a system of non-homogeneous linear equations with n unknowns and n equations, then the determinant of coefficient D = 0

Ax=b
If d = | a ≠ 0, then a is reversible
Multiply the inverse matrix A ^ (- 1) of a on the left and right sides of AX = b
Then we obtain x = a ^ (- 1) B, that is, the system of equations has unique solution
So if AX = B has no solution or infinite connections, d = 0 is required
Ax = B no solution also need to find R (a, b) ≠ R (a)
That is, the rank of the augmented matrix is not equal to the rank of the coefficient matrix

1.x(x-3)(x+1)(x-2)＜0 2.（30+7x-2x²）（x²+1）≤0

1. X (x-3) (x + 1) (X-2) < 0 threading method: - ╮╭ - - ╮╭ - - - - O -------- o -------- > - 1 system - ╯ 0 2 system - ╯ 3, X solution set is (- 1,0) U (2,3) 2. (30 + 7x-2x & ╭) (X & ╭ + 1) ≤ 0 X & ╯ 178; + 1 > 0 hengchengyuan

-|-The absolute value of 3 and 2 / 3 |

-|-Three and two thirds|
=-3 and 2 / 3
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4x+9y=12 3y-2y+5z=11 5x-6y+7z=13
How much is x, y, Z

4x+9y=12 …… （1）
3x-2y+5z=11…… （2）×7
5x-6y+7z=13…… （3）×5
21x-14y+35z=77…… （4）
25x-30y+35z=65…… （5）
（4）-（5）
-4x+16y=12…… （6）
(1)+(6)
25y = 24, y = 24 / 25, substituting (6)
x=4×24/25-3=21/25
z=(11-3×21/25+2×24/25)/7
=260/175=52/35

Xiao Gang, Xiao Li and Xiao Ming each have some pictures. The ratio of the three is 8:5:2. Xiao Li has 30 pictures. How many pictures do Xiao Gang and Xiao Ming have?