How to calculate the set of all subsets

How to calculate the set of all subsets

The number of subsets of any finite set is 2 ^ n;
The number of all subsets of {1,2,3,4,5,6} is 2 ^ 6 = 64
On the problem of finding the number of set subsets in higher one
Given that {a, B} &; a really contains {a, B, C, D, e}, then the number of sets a?
Is that really included really included?
A1={a,b,c,d,} .A7={a,b}
There are seven
There are five elements in ∵ {a, B, C, D, e} and two elements in {a, B}
The number of a is 2 ^ (5-2) - 1 = 7
The number of subsets of a finite set of n elements
If it is a proper subset, then it is (n power of 2) - 1; if it is a non empty proper subset, then it is (n power of 2) - 1,
2^n
2 ^ n nonempty proper subset: 2 ^ n minus 2
N-th power of 2~
Nonempty proper subsets are n-2 of 2
Junior high school learned positive proportion function, inverse proportion function, linear function, quadratic function, in its region when the function increases, when to decrease
Speed, big brother and big sister
There is a mistake in the domain. Sorry
Positive scale function
Monotonically increasing on R when y = KX k > 0
K0
x> 0 and X-B / 2A monotonically increasing
X
Linear function
Y = KX + B can be understood as y-b = KX
k> Monotonically increasing on R at 0
K0 opening upward, x > - B / 2A monotonically increasing
X
It is known that F 1 and F 2 are the two focal points of the ellipse. If the circumference of △ AF 1b is 16 and the eccentricity of the ellipse is E32, we can find the chord ab of the ellipse through F 2
It is known that F 1 and F 2 are the two focal points of the ellipse. If the circumference of △ AF 1b is 16 and the eccentricity of the ellipse e = 3 / 2, the standard equation of the ellipse is obtained
Let F1 (- C, 0) and F2 (C, 0) be on the x-axis
Because the triangle af1b passes through F2,
So the triangle af1b = 2A + 2A = 16, a = 4, a ^ 2 = 16
Because e = C / a = radical 3 / 2
So C = 2 radical 3 C ^ 2 = 12
From A2-B2 = C2
b2=4
So the equation of ellipse is x2 / 16 + Y2 / 4 = 1
Because the circumference = (F1A + af2) + (f2b + BF1) = 2A + 2A = 4A (the sum of the distances from a point on the ellipse to two focal points is 2a)
So 16 = 4A, a = 4 and E = root 3 / 2, so C = 2 (root 4) B = 2, so the standard equation is X & # 178 / 16 + Y & # 178 / 4 = 1
How to calculate the x power of 3 equal to 45 with logarithmic formula
log_ 3(45)
=log_ 3(3*3*5)
=log_ 3(3^2)*5
=log_ 3(3^2)+log_ 3(5)
=2+log_ 3(5)
What is the learning order of primary function, positive proportion function and inverse proportion function in junior high school?
Positive proportion function, primary function, inverse proportion function
It is known that F1 and F2 are the two focal points of ellipse X & # 178 / A & # 178; + Y & # 178 / B & # 178; = 1, AB is the chord passing through F1, then what is the perimeter of triangle ABF?
It should be a triangle. What's the circumference of abf2?
A. B is on the ellipse, so there is:
AF1+AF2=2a,
BF1+BF2=2a
Perimeter of triangle abf2
=AB+AF2+BF2
=AF1+BF1+AF2+BF2
=AF1+AF2+BF1+BF2
=4a
The circumference of triangle ABF is 4a
AF1+AF2=2a,
BF1+BF2=2a
Perimeter of triangle abf2
=AB+AF2+BF2
=AF1+BF1+AF2+BF2
=AF1+AF2+BF1+BF2
=4a
The circumference of the triangle ABF is 4a
The power of the reduction index is the logarithm: n ^ (1 / LG (n)), that is, the power of n (1 divided by LG (n))
n^(1/lg(n))=n^(logn(10)/logn(n))=n^(logn(10))=10
Or, let: k = n ^ (1 / LG (n))
Take the common logarithm on both sides: LG (k) = (1 / LG (n)) * LG (n) = 1
That is: k = 10
n^(1/lg(n))=Y
lg(n^(1/lg(n))=lg(Y)
(1/lg(n))*lg(n)=1=lg(Y)
Y=10^1=10
It is known that the function f (x) is a positive proportion function, and the function g (x) is an inverse proportion function, and f (1) = 1, G (1) = 2. (1) find the function f (x) and G (x); & nbsp; & nbsp; & nbsp; (2) judge the parity of the function f (x) + G (x)
(1) Let f (x) = K1X, G (x) = k2x, where k1k2 ≠ 0, ∵ f (1) = 1, G (1) = 2, ∵ K1 × 1 = 1, K21 = 2, ∪ K1 = 1, K2 = 2, ∪ f (x) = x, G (x) = 2x; (2) let H (x) = f (x) + G (x), then H (x) = x + 2x, ∪ (0, +)