длина рычага 1 м где должна находится точка опоры чтобы груз массой 5 кг подвешенный на одном конце уравновешивался с грузом в 20 кг на другом конце?

sin2x-(корень3)cos2x=0 помогите)

еще помогите пожалуйста : log7 * 14 - log7 * 6 + log7 * 21

решите неравенство 14x-2>(2x-1)(x+5)

выбрать подходящий вариант.

 1. While I looked/was looking for my keys, I suddenly remembered I left/had left them at home.
2. In those days the unions used to/had used to go on strike whenever there was/was being a problem.
3. After they were buying/had bought the company, they started/were starting to make a lot of people redundant.
4. Jack used to have/was having a Mac, but then he used to change/changed to a PC.
5. I asked about my package in reception, but they said/were saying that it still hadn’t arrived/wasn’t arriving.
6. I was sure that I used to lock/had locked the door to my office last night, but it was/had been open this morning.
7. I’m sure that the winters used to be/had been colder when I was a child. I remember that we used to walk/were walking to school in the snow every winter.
8. I had gone/went back to the restaurant to look for my umbrella, but found/was finding that someone took/had taken it.
9. When George saw/was seeing Diane at the seminar, he knew/was knowing that he met/had met her somewhere before.
10. While I had/was having breakfast I looked/was looking at the financial pages to see the share prices. I saw/was seeing that my original investment grew/had grown by over 40%.