Сочинение на тему "Роль человека в природе!" срочно нужно сейчас!

Решите уравнения или хотя бы подскажите по какой формуле решать, пожалуйста! Заранее спасибо!

а) 1/16а * а - 1/25=0

б) 4/49b * b - 16/ 121=0

в) 9/16c * c - 81/100=0

г) 36/1225d * d - 64/441=0

P.S. * - это умножить.

Fill the gaps with the verb in brackets using the Past Perfect Continuous or the Past
Perfect.

Example:

We _____________ there since 1980, you know. (to stay) – We had been staying there since 1980, you know.

He had married her two years before we met. (to marry) – He had married her two years before we met.

1. When the student revolution came, I _____________ there for 6 months. (to work)
2. Before Jim finally decided to go to Thailand, he _____________ about it for months. (to think)
3. They _____________ all the chocolate cake by the time Michael got to the party. (to eat)

4. I ______________ Scarlet Johansson on three previous occasions. Lucky me! (to meet)
5. The forensic evidence shows that he _____________ his nose just before he was murdered. (to pick)
6. When the doctor told him his liver was seriously bad, he _____________ hamburgers for a month. (to eat)
7. Prior to the explosion, the fat man _____________ seven large chocolate cakes. (to eat)
8. When they cancelled the flight to Alicante, the storm _____________ all afternoon with no sign of abating. (to rage)

массовая доля кислорода в высшем оксиде элемента с порядковым номером 20 равна

А 28,6%

Б 50,45%

В 75,15%

Г 80%

Формула оксида_____

С2 найдите все значения параметра p, при которых уравнение (p+1)x^2+2px+p=0 имеет корни.