Объясните пожалуйста задание:
Не решая уравнения, выясните, имеет ли оно корни, и если имеет, то определите их знаки.
1) х²-7х+1=0
2) 5х²+17х+16=0
3) 19х²-23х+5=0
Именно ОБЪЯСНИТЕ!Спасибо заранее.

Read the text about the failed plot to blow up Parliament House and kill King James I. Some sentences have been removed from the text. Match the gaps 1-10 with the sentences A-K. There is one extra sentence you don’t need to use.

On 5 November 1605 King James I was going to Parliament packed with people for the yearly Royal State Opening of Parliament ceremony...

1) ______________________ . For more than a year a gang of men had been secretly plotting a huge explosion to blow up Parliament and the King. The gang were Catholics angry that the Protestant King and Parliament did not let Catholics practise their religion. 2)_____________________.

Robert Catesby was the brains behind the deadly plan. He couldn't work alone, so he gathered a group of seven men, including the famous Guy Fawkes, to help him. 3) ___________________.  The plot began in May 1604 when Guy Fawkes and Thomas Percy rented a house very close to Parliament. They then began to dig a tunnel...

4) ___________________ Well, the gang had a huge heap of gunpowder and wanted to get it into the most important building in the country without anyone noticing. 5) _____________________.

So, they dug, and dug and dug...

The tunnel was meant to connect the cellar of their house to the Houses of Parliament - perfect for smuggling that gunpowder.

Time ticked on and the plotters kept digging... until in March 1605 they had a stroke of luck.

6) ______________________. The plotters packed the cellar with 36 barrels of gunpowder. They covered the barrels with bundles of firewood to disguise them, just in case anyone looked inside.

Ten days to go. The gunpowder was ready. The plotters were ready. What could possibly go wrong? Well, a very mysterious letter upset their careful plans.

Lord Monteagle, a very important man and friend of King James I, was given a letter at dinner on October 26th 1605. 7) ______________________. The letter warned him not to go to the ceremony on November 5th as something terrible was going to happen. Monteagle didn't know what to make of the letter and he didn’t know who had written it. 8)________________________. The plotters found out about the letter but they still wanted to carry out their plot.

On November 5th 1605 the soldiers found Guy Fawkes and the gunpowder in the cellarso the plot failed. After his arrest in the cellar Fawkes was taken to see King James. 9)___________________. After his audience with the King, Guy Fawkes was put to the Tower of London. Eventually he revealed the names of the others under torture. 10) ____________________.

All seven were sentenced to be...  hung, drawn and quartered.

Since then every year on November 5th people celebrate Guy Fawkes night by letting off fireworks which are a reminder of the gunpowder Guy Fawkes hid in the cellar of Parliament. 

A  Was it a nasty joke or was it a serious warning?

B Their trial was at Westminster Hall in Parliament in January 1606.

C They managed to rent a cellar underneath the House of Lords.

D The king was angry as Guy Fawkes refused to say who the other plotters were.

E A tall, mysterious stranger had handed it to his servant in the street earlier in the evening.

F Not an easy thing to do.

G So, they thought that the King deserved to die.

H Everything seemed ready.

I Why a tunnel?

J He did not know that everyone in the building would be in grave danger.  

K The gang's plan came to be called the Gunpowder Plot.