When 0 ＜ x ＜Π / 4, what is the minimum value of the function f (x) = cosx square / (cosxsinx SiNx Square)

When 0 ＜ x ＜Π / 4, what is the minimum value of the function f (x) = cosx square / (cosxsinx SiNx Square)

The numerator denominator is divided by cosx square f (x) = 1 / TaNx Tan square
Because 0

One group of students went for a spring outing, and the estimated supply and demand cost was 1200 yuan. Later, another group of students came in, and the total cost remained unchanged, so no one could share 60 yuan less
Given that the number of students in these two groups is equal, what is the number of students in each group?

Suppose there are X students in each group. If there is no one y yuan before the number is increased, there will be
XY=1200
2X(Y-60)=1200
Solve the above equations
There are x = 10, y = 120
A: there are 10 people in each group

Solution Lim / (x → 0) sin2x / X

lim／（x→0 ）sin2x／x=lim／（x→0 ）2cos2x=2

If A-B = 5, then what is the square of (1-2a + 2b)?

Let's start all over again

Let's begin again
Let's restart
Let's make a fresh start

How many mu of 15000 square meters

15000 square meters = 22.5 Mu

(1/2+1/3+...+1/2000)*(1+1/2+...+1/1999)-(1+1/2+...+1/2000)*(1/2+1/3+...+1/1999)

Analysis: in the first part of the formula, it is easy to use the law of multiplication and distribution
Original formula = (1 / 2 + 1 / 3 +... + 1 / 2000)+
(1/2+1/3+...+1/2000)×(1/2+...+1/1999)-(1+1/2+...+1/2000)*(1/2+1/3+...+1/1999)
=(1/2+1/3+...+1/2000)+(1/2+...+1/1999)×[(1/2+1/3+...+1/2000)－(1+1/2+...+1/2000)]
=(1/2+1/3+...+1/2000)+(1/2+...+1/1999)×(-1)
=(1/2+1/3+...+1/2000)+(-1/2-...-1/1999)
=1/2+1/3+… +1/2000-1/2-1/3-… -1/1999
=(1/2-1/2)+(1/3-1/3)+… +(1/1999-1/1999)+1/2000
=0+0+… +0+1/2000
=1/2000

Ask the meaning of two English words
frdb indexdb

The first one is definitely not a word because there are no vowels
The second one doesn't seem to be either

In the arithmetic sequence {an}, it is known that A6 = 10, S5 = 5, find (1) find A8 and S8, and (2) the sum of 10 consecutive terms from A6

S5=5A3=5 A3=1；A6=10；d=（A6-A3）/3=3
A8=A6+2d=16
S8=8A8-8*7/2*3=128-84=44
Or S8 = S5 + 3a7 = 5 + 3 (A6 + D) = 44
A6+…… +A15=S15-S5=15A8-S5=235

2X + 3Y + Z = 1 x + y + Z = - 2 3x-2y-z = - 4 find x, y, Z

2x+3y+z=1 …… （1）
x+y+z=-2 …… （2）
3x-2y-z=-4…… （3）
（1）-（2）
x+2y=3…… （4）
（2）+（3）
4x-y=-6…… （5）
（4）*4-(5)
9y=18 y=2
Substitute (4) to get x + 4 = 3, x = - 1
Substitute (1) to get - 2 + 6 + Z = 1, z = - 3