2x^2+xy-y^2-4x+8y-6

2x^2+xy-y^2-4x+8y-6

We should change 6 to 16, then we can get (2x-y + 4) (x + y-4), take the above formula equal to 0, take x as the unknown, if Δ is the complete square formula, the constant term must be 16, so it is easy to get

How to find the minimum value of 2x & sup2; - 4xy + 4Y & sup2; - 8x + 2016

Man, it's very simple. The steps are as follows:
2x²-4xy+4y²-8x+2016=x²-8x+16+x²-4xy+4y²+2000
=(x-4)^2+(x-2y)^2+2000
Obviously (x-4) ^ 2 and (x-2y) ^ 2 are greater than or equal to zero, so the minimum value of (x-4) ^ 2 + (x-2y) ^ 2 is zero. Then add 2000, the minimum value is 0 + 2000 = 2000
Therefore, the minimum value of 2x & sup2; - 4xy + 4Y & sup2; - 8x + 2016 is 2000
Answer finished, give points

Finding the extremum of function f (x, y) = x ^ 3-4x ^ 2-2xy-y ^ 2
Sorry, the problem is wrong, it's + 2XY
The answer is the maximum f (0,0) = 0, which I can't work out

Solution f'x (x, y) = 3x ^ 2-8x-2y = 0 f'y (x, y) = - 2y-2x = 0
Get x = 0,2, y = 0, - 2
For the first set of solutions 0,0
fxx(0,0)=-8 fxy(0,0)=-2 fyy(0,0)=-2
-8 * - 2 - (- 2) ^ 2 = 12 > 0 and - 8

Find the extremum of the following functions: (1) f (x) = 6 & # 178; - X-2; (2) f (x) = x & # 179; - 27x
Find the extreme value of the following function:
(1)f(x)=6²－x－2；
(2)f(x)=x³-27x.
Please write down the process of solving the problem. Thank you very much

Is there a question in question (1) f (x) = 6 & # 178; - X-2 should be (1) f (x) = 6x & # 178; - X-2; or (1) f (x) = x & # 178; - X-2?

A number is 0.6 less than 75% of 12.8. What's the number?

12.8 × 75% - 0.6 = 9.6-0.6 = 9

The result is that the coefficients of the numerator and denominator of the fraction [(5 / 6) x + y] / [(3 / 2) x - (7 / 4) y] are all integers

The numerator and denominator are multiplied by 12 at the same time
(10x+12y)/(18x-21y)

Take off the formula calculation (can be simple to calculate) quickly!
4 / 5-16 / 13 + 16 / 5 / 8 / 7 - (2 / 5 + 1 / 10) 5 / 8 + (22 / 27-8 / 5) 12 / 11-2 / 1-3 / 1 7 / 6 + 6 / 1 - (3 / 8-7 / 1)

1, 4 of 5-16 / 13 + 5 of 16 = 4 of 5 - (13 of 16-16 / 5) = 4 of 5-16 / 8 = 32 of 10, 7 of 8 - (2 of 5 + 1 of 10) = 7 of 8-2 / 1 = 13 of 8, 5 of 8 + (22 of 27-5 of 8) = 5 of 8-8 / 5 + 22 of 27 = 224 of 27, 11 of 12

0 is () A. positive B. negative C. non positive D. rational
Zero is not a positive number, is not a negative number, but zero is also a rational number, crazy!
Our math teacher said that all the multiple choice questions in grade one are single choice, not multiple choice, but there is such a question: 0 is () A. positive number B. negative number C. non positive number D. rational number
It's not only a non positive number, but also a rational number. But it's right to say that 0 makes a non positive number and a rational number -
And 0 is "not a positive number", which is still true!

Your understanding is right
0 is not a positive number, but also a rational number
That is, C and D are all right,
It's a question of the title

If the solution of the equations 3x + 5Y = 6 ① 6x + 15y = 16 ② is also the solution of the equation 3x + KY = 10, then the value of K is ()
If the solution of the system of equations 3x + 5Y = 6 ① 6x + 15y = 16 ② is also the solution of equation 3x + KY = 10, then the value of K is (?)
A、K=6 B、K=10 C、K=9 D、K=1/10
It's right

2 * ① - ②,
y=4/5,
x=2/3,
In the case of 3x + KY = 10,
So, k = 10

Five math problems, (each problem must be solved by formula!)
1. The school takes part in the tree planting day activities, which are divided into five groups, nine groups and 15 groups, all right. How many students are there at least?
2. The starting point of the new century garden style bus No.8 and No.11 is that No.8 bus leaves every 8 minutes and No.11 bus leaves every 10 minutes?
3. The distance between the two lanterns is 15 meters. Now it's 20 meters. If the one at the starting point doesn't move, how far away is there another one that doesn't need to move?
4. Use 96 red flowers and 72 yellow flowers to make a bouquet. If the number of red flowers in each bouquet is the same, so is the number of yellow flowers. How many flowers are there at least in each bouquet?

1. 15 / 5 = 3,9 / 3 = 3, total number = 3 * 5 * 3 = 45; the least common multiple of 2,8 and 10, 8 = 2 * 2 * 2,10 = 2 * 5, time = 5 * 2 * 2 = 40; the least common multiple of 3,15 and 20 to the multiple of 15, 15 = 3 * 5,20 = 2 * 2 * 5, the least common multiple = 3 * 2 * 2 * 5 = 60, the 60th / 15 = 4 do not move position; 4