If integers x and y satisfy the inequality x2 + Y2 + 1 ≤ 2x + 2Y, then the value of X + y has () A. 1 B. 2 C. 3 d. 4

If integers x and y satisfy the inequality x2 + Y2 + 1 ≤ 2x + 2Y, then the value of X + y has () A. 1 B. 2 C. 3 d. 4

The deformation of x2 + Y2 + 1 ≤ 2x + 2Y is that, x2-2x + 1 + y2-2y + 1 ≤ 1, (x-1) 2 + (Y-1) 2 ≤ 1, and (x-1) 2 ≥ 0, (Y-1) 2 ≥ 0, the following conditions can be obtained: X − 1 = 0y − 1 = 0 or X − 1 = ± 1y − 1 = 0 or X − 1 = 0y − 1 = ± 1, so the value of X + y has 2, 3 and 1, so it should be selected: C

Let m, M + 1 and M + 2 be the lengths of the three sides of an obtuse triangle, then the value range of the real number m is ()
A. 0＜m＜3B. 1＜m＜3C. 3＜m＜4D. 4＜m＜6

If m, M + 1 and M + 2 are the lengths of the three sides of an obtuse triangle, and the obtuse angle of the largest pair of sides m + 2 is α, then cos α = M2 + (M + 1) 2 − (M + 2) 22m (M + 1) = m − 3M ＜ 0 and 0 ＜ m ＜ 3 can be obtained from the cosine theorem. Then M + m + 1 ＞ m + 2 and 〈 m ＞ 1 can be obtained according to the sum of any two sides is greater than the third side

It is known that the parabola y = a (X-H) ^ 2 + K has a downward opening and its vertex is in the second quadrant. To prove that the equation AX ^ 2 + HX + k = 0 about X must have two unequal real roots

Therefore, there must be two unequal real roots

Finding the second order partial derivative of Z = x ^ 2Y
Economic mathematics book on a problem ~ for help

z=x^2y
∂z/∂x=2y*x^(2y-1)
∂z/∂y=x^2y*2lnx
∂^2z/∂x^2=2y*(2y-1)*x^(2y-2)
∂^2z/∂y^2=x^2y*4(lnx)^2
∂^2z/∂x∂y=2*x^(2y-1)+4ylnx*x^(2y-1)

Put 4 pieces on each side of a square. How many pieces can you put on each side at most? How many pieces can you put on each side at least?

14

The maximum value of quadratic function y = - x ^ 2 + 4x-6 is

y=-(x^2-4x+4)+4-6
=-(x-2)^2-2≤-2
So the maximum value = - 2

When k is a value, the function y = 3 (K + 1) x ^ k ^ 2-k-3 is an inverse proportional function

If the function y = 3 (K + 1) x ^ k ^ 2-k-3 is an inverse proportional function, then there are: K & # 178; - K-3 = - 1 and K + 1 ≠ 0, that is to say, K ≠ - 1 equation K & # 178; - K-3 = - 1 is transferred to: K & # 178; - K-2 = 0 (K-2) (K + 1) = 0, and the solution is: k = 2 (k = - 1 is not the problem, so when k = 2, function y = 3 (K + 1) x ^ k ^ 2-k-3 is an inverse proportional function

The absolute values of LIM (1 + a 2 + a 3 +... + an) / (1 + B 2 + B 3 +... + BN) a and B are less than 1 (2, 3, n are all power}

lim(n→∞) (1+a^2+a^3+… +a^n) / (1+b^2+b^3+… +b^n)
=Lim [1 + A ^ 2 * (1-A ^ (n-1)) / (1-A)] / ([1 + B ^ 2 * (1-B ^ (n-1)) / (1-B)], equal ratio summation formula
=[ 1+a^2/(1-a) ] / ([ 1+b^2/(1-b) ]
=(1+a^2)(1-b) / (1+b^2)(1-a)
If you don't understand, please ask

In the triangle ABC, AC = BC, ad is the height on the side BC, AE is the bisector of ∠ BAC, if ∠ ead = 18 degrees, then ∠ ACD = how many degrees
Master, please answer with the picture above

Suppose that ∠ B = x °,'ac = BC, AE is the bisector of ∠ BAC, ′ ∠ BAE = x / 2 °, and ∠ AED = ∠ B + ∠ EAB = 3x / 2 ° and ','ad is the height on the side BC, ∠ ead = 18 °, and' ∠ AED = 90-18 = 72 ° = 3x / 2 ° and ', x = 48 °, ACD = 180 ° - 2x ° = 84 °

600 square decimeters=______ Square centimeter=______ Square meters

600 square decimeter = 60000 square centimeter = 6 square meter