Y = 2cos square x + 5sinx-4, and find the corresponding x value

Y = 2cos square x + 5sinx-4, and find the corresponding x value

y=2(1-sin²x)+5sinx-4
=-2sin²x+5sinx-2
formula
=-2(sinx-5/4)²+9/8
The opening is downward and the axis of symmetry SiNx = 5 / 4
Because - 1

Given the function f (x) = 2cos square x + 2sinxcosx (1), find the minimum positive period of function f (x) (2) find the monotone increasing interval of function f (x)
In the known arithmetic sequence {an}, A3 = 5, A9 = 17, the nth term BN = 81 / an + 2n (1) of the sequence {BN} and the general term formula (2) of the sequence (an) are obtained. If the inequality BN > = 1 / a holds, the value range of a is obtained

Using the formula of double angle, the following results are obtained
F (x) = cos2x + sin2x + 2 = radical 2Sin (2x + pi / 4) + 2
So, the minimum positive period is pi,
The monotone increasing interval is: - pi / 2 + 2kpi

If real numbers x, y and Z satisfy (x-z) 2-4 (X-Y) (Y-Z) = 0, then the following formula must be true ()
A. x+y+z=0B. x+y-2z=0C. y+z-2x=0D. z+x-2y=0

∵ (x-z) 2-4 (X-Y) (Y-Z) = 0, ∵ x2 + z2-2xz-4xy + 4XZ + 4y2-4yz = 0, ∵ x2 + Z2 + 2xz-4xy + 4y2-4yz = 0, ∵ (x + Z) 2-4y (x + Z) + 4y2 = 0, ∵ (x + z-2y) 2 = 0, ∵ Z + x-2y = 0

A batch of machine parts can be processed in 12 hours by the master and apprentice. First, the master processes 8 hours, and then the apprentice processes 6 hours
It is known that the master makes 10 more parts per hour than the apprentice. How many parts are there in total?

The master does it for 8 hours first and then the apprentice does it for 6 hours, which can be regarded as the cooperation between the master and the apprentice. After 6 hours, the master does it for 2 hours, that is, 3 / 5 of the task is completed, that is, 6 hours in total: 6 * 1 / 12 = 1 / 2. Then the master does it for 2 hours: 3 / 5-1 / 2 = 1 / 10, that is, the master does it for 1 hour: (1 / 10) / 2 = 1 / 20), and the apprentice does it for 1 hour: 1 / 12-1 / 20 = 1

Solving the equation of 8x-8 × 3 = 2x

There are 100 tons of grain in warehouse A and 80 tons in warehouse B. how many tons of grain are taken from warehouse A and distributed to warehouse B? The ratio of grain in warehouse A and warehouse B is 7:11?

7 + 11 = 18100 - (100 + 80) × 718 = 100-180 × 718 = 100-70 = 30 tons. A: after 30 tons are taken from warehouse A and distributed to warehouse B, the ratio of grain in warehouse A and warehouse B is 7:11

Equation X-2 / 7X - [2 / 7X + 1600] * 1 / 2 = 1600 detailed steps

X-2/7X-[2/7X+1600]*1/2=1600
x-2/7x-1/7x-800=1600
4/7x=2400
x=4200

Put the nine numbers 1.3.5.7.9.11.13.15.17 into the box below to make the three numbers on the horizontal, vertical and oblique lines

3 17 7
13 9 5
11 1 15

The sum of the first n terms of the proportional sequence Sn = 5 * 3 ^ (n-1) + A, a is equal to

The sum of the first n terms of the equal ratio sequence Sn = 5 * 3 ^ (n-1) + A
So q = 3, A1 = S1 = 5 + A
So Sn = A1 (1-Q ^ n) / (1-Q) = (5 + a) (1-3 ^ n) / (1-3) = (5 + a) * 3 ^ n / 2 - (5 + a) / 2
So 3 (5 + a) / 2 = 5, a = - (5 + a) / 2
So a = - 5 / 3
If you don't understand, I wish you a happy study!

1. For a job, Party A and Party B work together for 36 days. Party A will work alone for 20 days, and Party B will work alone for another 40 days. How many days will it take for Party B to complete the job alone?
2. A, B and C will practice long-distance running on the ring track again. It takes 1 minute 12 seconds for a lap, 1 minute 20 seconds for B lap, and 1 minute 30 seconds for C lap. Three people start at the same place at the same time. How long will it take at least for them to appear at the starting point at the same time

1
(40-20)/(1-20/36)=45
two
72, 80 and 90 seconds respectively
Is to find the smallest number that can divide these three numbers
72=8x9
80=8x10
90=9x10
That's 8x9x10 = 720 seconds = 12 minutes