Masters, help me Youmu has a master to help me, hey.

1) The monitor is powered off, or the monitor data cable is in poor contact. In addition, the computer has been used for a long time, and the power cord of the monitor is easy to oxidize and break;

2) There is no power supply to the motherboard;

3) Poor contact or damage to the graphics card;

4) Poor CPU contact;

5) Poor contact of memory modules;

6) The machine is infected with CIH virus, and the BIOS is refreshed destructively;

7) Check the plugging and unplugging, if necessary, you can use a rubber to remove the oxide film on the gold finger;

8) If the floppy drive has a floppy disk, many times it will cause the computer to start or restart, and the computer will have a black screen and cannot enter the system. To avoid such situations, it is also possible to cancel the floppy disk boot item in the BIOS.

1. The quality of the memory, the memory is not plugged in properly, and the gold finger of the memory is dirty: the gold finger can be cleaned with anhydrous alcohol or an eraser.

Don't plug the memory upside down.

2. The problem of the graphics card, the signal cable of the graphics card is not connected, and the gold finger of the graphics card is dirty: the same memory.

3. The display is not set properly, and the brightness The display cannot withstand the high-resolution processing of the graphics card: adjust the brightness button.

4. The power supply contact is not good.

5. Fake black screen caused by system settings For example: screensaver.

Should be on the graphics card problem, you take the graphics card down, use the eraser to wipe the gold bar below, and then clean up the dust on the motherboard to see if it can be solved, if it still doesn't work, you can remove the accessories from the motherboard one by one to clean up and then install them, see which hardware is wrong.

Enter Safe Mode, Antivirus, or Restore an earlier setting, but you can't tell yet.

Has the system been fixed?

If you still have questions, please go to my space dedicated post to ask questions and be happy to help.

The cable connecting the main unit to the monitor is loose.

The monitor is broken, let's get another one.

There's something wrong with your hardware.

Caught in the variant of the Lira virus, it is recommended to do it from the system.

2013 is equal to 2013/2014 in addition to the disturbance.

2013x 2014/(2013x2014+2013)

2013x2014 Smile Spike (2013x2015).

1) M n, (2b-c) a cosc cosa, (2sinb+sinc) sina cosc cosa, to obtain cosa 1 2, a 60

2) y=2(sinb) 2+cos( 3-2b)1-cos2b+1 2cos2b+root numberLuwang3 2sin2b1+root number3 Huaishen 2sin2b- 2cos2b1+sin(2b-30°).

And because lead loses a=60° then 0, 1 2<1+sin(2b-30°)<2