In the following formula, add the operation symbols (+, -, x, Division) and brackets to make the equation hold. 9 = 0

In the following formula, add the operation symbols (+, -, x, Division) and brackets to make the equation hold. 9 = 0

(9+9÷9)×(9-9)=0

If the eigenvalues of the third order matrix A are all 0, what is R (a)
What is the relationship between the eigenvalues of a matrix and its rank

3

A three digit number. The sum of the numbers in each digit is equal to 3. What is the minimum and maximum of this number

Minimum 102
Max 210

B is the invertible matrix of a, and a * b = E. prove rank (AB) = rank (BA)?

What's the problem
AB=BA=E
r(AB) = r(BA) = n

How many girls are there? There are 252 girls, X boys and 18 girls

2x+18=252
2x=252-18
2x=234
x=117
So there are 117 girls
Boys are 117 + 18 = 125
Verification: 117 + 125 = 252 is consistent with the proposition

On the polynomial of X, y, BMX's 2 square + 4nxy + 2x + 2xy-x's 2 square + y + 4 does not contain quadratic term, find the value of bm-2n + 2

BMX ^ 2 + 4nxy + 2x + 2xy-x ^ 2 + y + 4 = (BM-1) x ^ 2 + (4N + 2) XY + 2x + y + 4 merge congeners
If there is no quadratic term, then the coefficient of quadratic term is 0, that is BM-1 = 0, 4N + 2 = 0, so BM = 1, n = - 1 / 2
So bm-2n + 2 = 1-2 × (- 1 / 2) + 2 = 1 + 1 + 2 = 4

Calf read a book. On the first day, he read one sixth more than six pages. On the second day, he read one eighth less than eight pages. There are 172 pages left in the book
Calf read a book. On the first day, he read one sixth more than six pages. On the second day, he read one eighth less than eight pages. There are 172 pages left in this book. How many pages are there in this book?

Let the book be x pages in total, so 1 / 6x + 6 + 1 / 8x-8 + 172 = X. the final result is 240 Pages

When Wang Ming calculated the difference of a polynomial minus 2B ^ + b-5d, he forgot to enclose the two polynomials in brackets

Isn't it B ^ 2 + 6 + 9? That's the answer. hey!!!

A truck and a car drive from a to B at the same time. The car returns immediately after arriving at B, and the speed increases by 50%. Two hours after departure, the car and the truck meet for the first time. When the truck arrives at B, the car just goes to the midpoint of a and B. how long does it take for the car to go back and forth between a and B?

Let the speed of the car go to x, then the speed of the car return is: (1 + 50%) x = 32x, the time for the truck to complete the whole journey is: 1x + 12 △ 32x = 43x (hours), the speed of the truck is: 1 △ 43x = 34x, the distance for two cars to meet and walk together is the whole journey: 1-34 = 14

How to draw the number axis

The number axis is a straight line with a unique origin, a unique positive direction and a unique unit length. All rational numbers can be represented by the points on the number axis
Specific steps:
1. Draw a straight line with a ruler
2. Determine the origin (indicated by black dot) and positive direction (indicated by arrow)
3. Determine the unit length and use the scale to assist drawing
4. Write the scale value of each paragraph