4/x=0.2/1.

4/x=0.2/1.

4×1.5=0.2X
6=0.2X
X=30

（0·5+x）：3=1/2：3/4

Simple

If the right branch of the straight line y = KX + 2 and hyperbola x2-y2 = 6 intersect at two different points, then the value range of K is ()
A. (−153，153)B. (0，153)C. (−153，0)D. (−153，−1)

The asymptote equation is y = ± x, y is eliminated from y = KX + 2x2 − y2 = 6, and (k2-1) x2 + 4kx + 10 = 0  K ＜− 1 △ = (4K) 2 − 40 (K2 − 1) ＞ 0 {− 153 ＜ K ＜− 1, so D is selected

Remove the parentheses, and the symbols inside the parentheses remain unchanged

To see the symbol before the brackets,
If it is "+", the symbol inside the brackets will not change
If it is "-", the symbol inside the parentheses will change

Let a > 1, b > 1, log2 (a) × log2 (b) = 1
Why log2 (a) > 0?

Because a > 1, b > 1, so log2 (a) > 0, log2 (b) > 0, let a = log2 (a), B = log2 (b)
Then AB = 1, log2 (AB) = a + B, so if and only if a = b = 1, the minimum of a + B is 2
Because log2 (x) is an increasing function, if a > 1, log2 (a) > log2 (1) = 0

(a + 2B + 1) (- A + 2b-1) + (A-1) square reduction

（a+2b+1)(-a+2b-1)+(a-1)²
=4b²-(a+1)²+(a-1)²
=4b²+[a-1+a+1][a-1-(a+1)]
=4b²-4a
Using the square difference formula

Let s be a set of real numbers satisfying the following conditions
1. Excluding 1
2. If a ∈ s, then 1 / 1-A = s
Q: if 2 ∈ s, study the number of elements in S and find out these elements; how to do detailed thinking steps
The answer is - 1, 1 / 2, 2

Because the set s satisfies a ∈ s, then 1 / 1-A = s,
So if 2 ∈ s, then there must be 1 / (1-2) = - 1 ∈ s
And because - 1 ∈ s, then 1 / [1 - (- 1)] = 1 / 2 ∈ s,
And because 1 / 2 ∈ s, then 1 / (1-1 / 2) = 2 ∈ s,
So the element in S is only - 1,1 / 2,2

Is the pronunciation of "W" and "U" the same in pinyin?

Same

1. If there is no common point between circle X & # 178; + Y & # 178; - 4x + 8y = 5 and circle X & # 178; + Y & # 178; - a = 0, then the range of a is
2. If the center of the circle O1 (- 2,0) O2 (2,0) is known, the radii of the two circles are 1, and the passing point P is tangent PM and PN of the circle O1 O2 respectively (m, n are tangent points), so that PM = radical 2 (PN), then the trajectory equation of the moving point P is

1. If there is no common point between circle X & # 178; + Y & # 178; - 4x + 8y = 5 and circle X & # 178; + Y & # 178; - a = 0, then the range of a is analytic: ∵ circle X & # 178; + Y & # 178; - 4x + 8y = 5 and circle X & # 178; + Y & # 178; - a = 0, no common point (X-2) ^ 2 + (y + 4) ^ 2 = 25; X ^ 2 + y ^ 2 = a, the center distance of two circles d = √ (4 + 16) = 2 √ 5 when 5 - √ a

Sixth grade percentage calculation

The number of male students participating in mathematics competition in a school is 4 times less than that of female students, 8 times less than that of female students, 24 times more than that of female students. How many male students and how many female students are participating in mathematics competition in this school? 2