Вопрос школьника по предмету Алгебра
Решите уоавнение 3tgx+2ctgx=5
Ответ учителя по предмету Алгебра
3tg x + 2ctgx = 5
Замена: tg x = t ⇒ ctg x = 1/t
3t + 2/t − 5 = 0 | · t
3t² − 5t + 2 = 0
t = 1
t = 2/3
Вернемся к нашей замене:
tg x = 1 ⇒ x = π/4 + πk, k — целое
tg x = 2/3 ⇒ x = arctg (2/3) + πn, n — целое
ОТВЕТ:
x = π/4 + πk, k — целое
x = arctg (2/3) + πn, n — целое
Похожие вопросы от пользователей
1.How people used to treat them
2.How they get their food
3.Where they live
4.How people start to collect their images
5.How they confuse the scientists
6.When they scare the people
7.How they breed
8.What endangers them
A.Flamingos are very social and often live in large groups, called colonies, throughout the world. They are found in both the Eastern and W estern hemispheres. The American Flamingo is the only one th at lives in the wild in North America, and on many Caribbean islands such as the Bahamas, Cuba, and Hispaniola. It also lives in northern South America, the Galapagos Islands, and parts of Mexico.
B.Flamingos fish while walking in shallow w ater and mud. W hen a flamingo notices its potential dinner (for example, shrimp, snails, and plantlike w ater organisms), it plunges its head into the water, tw ists its head upside down, and scoops the fish up using its upper beak like a shovel. Flamingos get their pink coloring from the carotenoid pigment in their food, which is the same pigment th at makes carrots orange.
C.Flamingos build nests th at look like mounds of mud along waterways. The parents take turns sitting on the egg to keep it warm and after about 30 days the egg hatches. Young flamingos are born white, with soft, downy feathers and a straight bill. Both adult birds look after the newborn flamingo. The young leave the nest after about five days to join other young flamingos in small groups, returning to their parents for food.
D.Scientists aren’t 100% sure why flamingos stand on one leg, but they have some theories. One theory says th at it is to keep one leg warm. Another idea is th at flamingos are drying out one leg at a time. A third theory states that it helps them deceive their catch, because one leg looks more like a plant than do two. W hatever the reason, it is truly amazing that these top heavy birds can balance on one leg for hours at a time.
E.Ancient Egyptians believed th at flamingos were the living representation of the god Ra. In the Americas, the Moche people of ancient Peru worshipped nature and paid a great deal of attention to these birds and often depicted flamingos in their art. However, Andean miners killed flamingos for their fat, which is believed to be a remedy for tuberculosis, and in Ancient Rome their tongues were considered
a delicacy.
F.Many people have plastic flamingos in their yards as ornaments. This is a fun and inexpensive way to add some elegance to one’s landscaping. In many parts of the world flamingos are popular collectibles, appearing in the form of magnets, water globes, and jewelry. They are also said to be an image that people find to be calming and exciting at the same time. For these purposes people buy millions of plastic flamingos annually all around the world.
G.Flamingos have been affected in many ways by global warming. One of the biggest concerns is making nests and laying eggs. Flamingos depend on rainfall to help
them mate and w ithout adequate rain they won’t engage in it. Many researchers find that global warming reduces the chance of rain and can cause drought in some of the areas where they live. This could mean a significant reduction of offspring in the years ahead.