We stipulate that "!" is an operation symbol, and 1! = 1,2! = 2 × 1,3! = 3 × 2 × 1,4! = 4 × 3 × 2 × 1 So The value of 2013 out of 2011 is A. 2012! B.2! C.2011 2013! D.4 050 156

We stipulate that "!" is an operation symbol, and 1! = 1,2! = 2 × 1,3! = 3 × 2 × 1,4! = 4 × 3 × 2 × 1 So The value of 2013 out of 2011 is A. 2012! B.2! C.2011 2013! D.4 050 156

Choose D
Because 2011! 2013! = 2011! 2011! × 2012 × 2013 = 2012 × 2013 = 4050156 = D option

It is proved that a is mxn matrix and B is nxm matrix

It is known that AB is MXM matrix
Because R (AB)

Rectangle area is 2.6 square meters, square area is 2 and 25 / 14 square meters, which figure area is larger

2 and 14 / 25 = 2,56 square meters
2.6-2.56 = 0.04 M2
A: the rectangular area is larger

Let a and B be homomorphic matrices, and prove that R (a + b) is less than or equal to R (a) + R (b)

Please see:

There is a column of numbers 6, 12, 18, 24······
(1) If the sum of three adjacent numbers is 306, which three numbers are they? (2) do there exist three adjacent numbers so that their sum is 2008? If there are, request these three numbers; if not, explain the reason

（1）96,102,108
Let the middle number be 6N and n be a positive integer, then the three numbers are 6n-6, 6N, 6N + 6
6n-6+6n+6n+6=18n=306,n=17
Then 6n-6 = 96, 6N = 102, 6N + 6 = 108
(2) 18N = 2008, n is not divisible, so there are no three numbers

Conversion of feet, inches and centimeters
How many feet is 181cm
How many inches are 80cm, 61cm and 92cm respectively

1 foot = 12 inches
1 inch = 2.54cm
181cm = 5.94 ft
80cm = 31.5in
61cm = 24 inches
92cm = 36.22 inches

10,8,6,4 are calculated as 24 points, and a comprehensive formula is given

1:(10 × (8 - 6)) + 42:10 × (8 - 6) + 43:(10 - 6) × 4 + 84:((10 - 6) × 4) + 85:8 + (10 - 6) × 46:8 + ((10 - 6) × 4)7:8 - (6 - 10) × 48:8 - ((6 - 10) × 4)9:(8 - 6) × 10 + 410:((8 - 6) × 10) + ...

If x.y satisfies X-2 + y + 1 = 0, then the value of B in 3x-2y = B + 7 is
If x.y satisfies X-2 + y + 1 = 0, then the value of B in 3x-2y = B + 7 is.

b=5x-9

A bus starts at 85 km / h, and two hours later a car runs in the same direction at 170 km / h. how many hours can it catch up with the bus

Pursuit time = distance difference △ speed difference
85×2÷（170-85）
=170÷85
=2 (hours)
A: catch up with the bus in 2 hours

The sum of the three sides of a triangle is 10, and the cosine of its angle is the root of the equation 2x ^ 2-3x-2 = 0······
The sum of the three sides of a triangle is 10, and the cosine of its angle is the root of the equation 2x ^ 2-3x-2 = 0. Find the minimum perimeter and the maximum area of the triangle
Process... Thank you··

Wrong title: should be
Given the triangle ABC, a + B = 10, and COSC is a root of the equation 2x ^ 2-3x-2 = 0, the minimum perimeter and the maximum area of the triangle ABC are obtained
2x^2-3x-2=0,
(2X+1)(X-2)=0,
X1=-1/2,X2=2,
Then COSC = - 1 / 2,
C = 120 degrees,
cos120=(a^2+b^2-c^2)/2ab=-1/2.
(a+b)^2-c^2=ab,
(a+b+c)(a+b-c)=ab,
Let y = a + B + C have
Y=ab/(a+b-c)=ab/(10-c),
To make y minimum, C must be minimum, then a and B must have maximum
A + B ≥ 2 √ AB, (a > 0, b > 0,) if and only if a = B, AB has the maximum value, that is, a + B = 10 = 2A, a = 5
cosC=cos120=(a^2+b^2-c^2)/2ab,
c^2=2*5^2-2*5*5*(-1/2)=25*3,
c=5√3.
Y=ab/(a+b-c)=ab/(10-c),
=25/(10-5√3)=10+5√3.
The minimum value of ABC perimeter of triangle is: 10 + 5 √ 3
a+b=10≥2（ab)^(1/2)
ab≤25
2x^2-3x-2=0
(2x+1)(x-2)=0
x=-1/2,x=2
So COSC = - 1 / 2
sinc=3^(1/2)/2
S△ABC=absinc/2≤25*3^(1/2)/2/2
=(25/4)*3^(1/2)
The maximum value is (25 / 4) * 3 ^ (1 / 2)