Today, Aunt Li's clothing store sold two pieces of clothes at the same time, each at 96 yuan. One of them earned 20% and the other lost 20%. Did Aunt Li make or lose money on these two pieces of clothes? How many yuan did she make or lose?

96÷(1+20%)=80 96÷（1-20%)=120
80+120=200
200-96 × 2 = 8 two clothes lost 8 yuan

6 yuan for a book, 6 copies for free, 15 copies at a time, how much cheaper is each

Buy 13 and get 2 free. That's enough for 15
That's 15 books for 13
15x6 = 90 yuan
13x6 = 78 yuan
90-78 = 12 yuan
12 / 15 = 0.8 yuan
So each one should be 0.8 yuan cheaper

For example, it costs 6 yuan more to buy 5 diaries than 1 story book. It is known that the price of a story book is just three times that of a diary, and how much is a diary

Suppose a diary costs X Yuan, then a story book costs 3x yuan
5x-6=3x
2x=6
x=3
Answer: a diary is 3 yuan

The rectangle ABCD, ab = 1, BC = 2 are known. The △ abd is folded along the straight line of the diagonal BD of the rectangle
A. There is a position where the line AC is perpendicular to the line BD. B. there is a position where the line AB is perpendicular to the line CD. C. There is a position where the line ad is perpendicular to the line BC. D. for any position, three pairs of lines "AC and BD", "AB and CD", "ad and BC" are not perpendicular

As shown in the figure, AE ⊥ BD, CF ⊥ BD, according to the title, ab = 1, BC = 2, AE = CF = 63, be = EF = FD = 33, a, if there is a certain position, making the straight line AC perpendicular to the straight line BD, then ⊥ BD ⊥ AE, ⊥ BD ⊥ plane AEC, thus BD ⊥ EC, which is in contradiction with the known, exclude a; B, if there is a certain position, making the straight line AB perpendicular to the straight line BD

Factorization: 1 / 2x ^ 2-2

1/2x^2-2
=1/2(x²-4)
=1/2(x+2)(x-2)

(1) There are n integers whose sum is zero and their product is n. verification: n is a multiple of 4; (2) let n be a multiple of 4 and verification: n integers whose product is n and their sum is zero can be found

It is proved that: (1) let n integers be A1, A2 A 1 a 2 an=n，a1+a2+… +If n is odd, then A1, A2 , an are odd numbers, so a1 + A2 + +An is the sum of odd numbers, which cannot be zero, so n must be even, so A1, A2 At least one of an is even, and if A1, A2 If there is only one even number in an, set A1, then A2 + a3 + +An is the sum of odd numbers (n-1), so it must be odd, so a1 + A2 + +An is odd, and a1 + A2 + +So A1, A2 There are at least two even numbers in an, so n = A1, A2 An can be divisible by 4. (2) let n = 4K. When k is odd, n = 2 · (- 2K) · 13k-2 · (- 1) k, and the sum of 4K numbers of 2, - 2K, (3K-2) 1 and k-1 is zero; when k is even, n = (- 2) (- 2K) · 13k-1) K-2, and the sum of 4K numbers of - 2, - 2K, 3K 1 and (K-2) 1 is zero

The distance between a vertex of the ellipse e: x ^ 2 / A ^ 2 + y ^ 2 / b ^ 2 = 1 (a > b > 0) and its two focal points F1 and F2 is 5 and 1 respectively. Point P is a point on the ellipse and above the x-axis. The slope of the straight line PF2 is - √ 15. The equation of the ellipse and the area of △ f1pf2 can be obtained

It is easy to get a + C = 5, a-c = 1, a = 3, C = 2 = > b & # 178; = 5. The elliptic equation is X & # 178 / / 9 + Y & # 178 / / 5 = 1. If P (m, n), n > 0, F2 (C, 0) = F2 (2,0), then K (PF2) = n / (m-2) = - √ 15 = > n = - √ 15 (m-2) because P is on the ellipse, the above formula is substituted into the ellipse

The product of two prime numbers must be______ ．

Prime x prime = product. The product is a multiple of two prime numbers. These two prime numbers are also the factors of the product. In this way, the factor of the product has these two prime numbers besides 1 and itself, so their product must be a composite number. So the answer is: composite number

The minimum value of the function y = x ^ 2-ax + 3 (a is a constant) when x belongs to [- 1,1] is - 1. Find the value of A
Let's talk about why we do this again. Thank you!

From y = x ^ 2-ax + 3, we can see that the axis of symmetry of the function is x = A / 2, and the opening of the function is upward
When a / 2 = 0, i.e. a = 0, the minimum value of the function is f (0) = 3, so a is not equal to 0
When a / 20, the minimum value of the function is f (1) = 1-A + 3 = - 1 a = 5
In conclusion, a = 5 or - 5

Given that f (x) = logax (a > 0 and a ≠ 1), if | f (x) | ≤ 1 holds for any x ∈ [13,2], try to find the value range of A

According to the meaning of the title, when 0 < a < 1, f (x) = logax monotonically decreases on [13,2], and loga13 > 0, loga2 < 0, | f (x) | ≤ 1, | loga13 ≤ 1 − loga2 ≤ 1, the solution is 0 < a ≤ 13; when a > 1, similarly, − loga13 ≤ 1, loga2 ≤ 1, the solution is a ≥ 3. In conclusion, the value range of a is (0,13] ∪ [3, + ∞)

Today, Aunt Li's clothing store sold two pieces of clothes at the same time, each at 96 yuan. One of them earned 20% and the other lost 20%. Did Aunt Li make or lose money on these two pieces of clothes? How many yuan did she make or lose?