When the function y = (sinx-a) is quadratic and SiNx = a, the minimum SiNx = 1 has the range of maximum a (why)

When the function y = (sinx-a) is quadratic and SiNx = a, the minimum SiNx = 1 has the range of maximum a (why)

Minimum value when SiNx = a
a≥-1
sinx=1
a≤1
-1≤a≤1

There are 20 students who go out for an outing and come to a canteen. They plan to drink a bottle of soda water for each student. The canteen stipulates that every five empty bottles can be replaced with a bottle of soda water. So
There are 20 students who go out for an outing and come to a canteen. They plan to drink a bottle of soda water for each student. The canteen stipulates that every five empty bottles can be replaced with a bottle of soda water. How many bottles of soda water should they buy at least?

16 bottles, please
After 15 bottles are drunk, 3 bottles can be changed for 15 empty bottles, and 1 extra bottle can be added. After drinking these 4 bottles, 19 people have finished, and 4 empty bottles are left
Borrow a bottle of soda, the last one has finished drinking, the remaining five empty bottles, change a bottle of soda, return, just in time

For two pieces of cloth of the same length, the first one takes 32 meters, and the second one takes 2O meters. As a result, the remaining meters of the second one are three times as many as the first one?

We know that x = y
3（x—32）=（y—20）
Do it by yourself, don't say you haven't learned function

A [i] [J] = (I 1) * (J) in the multiplication of two matrices

The sum of the products of the i-th row of the first matrix and the j-th column of the second matrix

Several students from the seventh grade interest group of a school rent a car to participate in the district mathematics competition. It is estimated that the rental fee is 5 yuan per capita, and then four students joined
As a result, each person lost two yuan. How many people were there?

If there were x people, we can get the following results
Analysis: the total amount of money is 5x
Later, the number of people is: (x + 4), the amount of money per person is: (5-2) the total amount of money available is: (5-2) (x + 4)
The total amount of money before and after is the same, so there are:}
5x=(5-2)(x+4)
5x=3x+12
5x-3x=12
2x=12
x=6
A: there were six

It is a complete step to find Lim [((1 + x) ^ (1 / x)) / E] ^ (- 1 / x) x → 0,

It is suggested to use Taylor expansion: notice that u ^ v = e ^ (vlnu), and ln (1 + x) = x-x ^ 2 / 2 + O (x ^ 2), so
lim [(1+x)^(1/x)/e]^(-1/x)
=lim [e^(ln(1+x)/x)/e]^(-1/x)
=lim [e^(x-x^2/2+o(x^2)/x)/e]^(-1/x)
=lim [e^(-x/2+o(x))]^(-1/x)
=lim e^(1/2+o(1))
=e^(1/2).
This problem can take logarithm, use lobita rule, but more cumbersome

Given A-1 / a = 1, and 2A ^ 4-3a ^ 2x + 2 / A ^ 3 + 2A ^ 2x-a = - 12 / 13, then the value of X is equal to (6) to process!

A-1 / a = 1 means: A ^ 2-A = 1 means: a = a ^ 2-1 and: A ^ 2 + 1 / A ^ 2 = 3 denominator: A ^ 3-A + 2A ^ 2x = a ^ 3-A ^ 2 + 1 + 2A ^ 2x = a ^ 2 * (a ^ 2-1) - a ^ 2 + 1 + 2A ^ 2x = a ^ 4-2a ^ 2 + 2A ^ 2x + 1, so the original formula = (2a ^ 4-3a ^ 2x + 2) / (a ^ 4-2a ^ 2 + 2A ^ 2x + 1) = - 12 / 13 means: 26a ^ 4-39a ^ 2x + 26 = - 12a ^ 4 + 24a ^ 2-24

I have lived here for more than 3 years

I have been living here for more than 3 years

What is the idiom of "fifteen minutes equals one thousand yuan"?

A minute is a thousand gold

(1-1/2)x(1-1/3)x(1-1/4)x.x(1-1/1999)x(1-1/2000)

(1-1/2)x(1-1/3)x(1-1/4)x.x(1-1/1999)x(1-1/2000)
=1 / 2x2 / 3x3 / 4x.x1998/1999x1999/2000, the numerator and denominator cancel each other
=1/2000