Giải thích các bước giải:
Vì $a,b,c$ là 3 cạnh tam giác $\to a+c>b,a+b>c\to a-(b-c)>0, a+(b-c)>0$
$\to (a-(b-c))(a+(b-c))>0$
$\to a^2-(b-c)^2>0$
$\to a^2+2bc-b^2-c^2>0$
$\to a^2+2bc>b^2+c^2$
Ta có :
$a^2+2bc>b^2+c^2$
$⇔a^2+2bc-b^2-c^2 > 0 $
$⇔a^2-(b-c)^2 > 0 $
$⇔(a-b+c).(a+b-c) > ) $ ( Đúng theo BĐT tam giác )
Bài học gì được rút ra từ ý nghĩa của câu tục ngữ : “Đêm tháng năm chưa nằm đã sáng Ngày tháng mười chưa cười đã tối”
Exercise 2: Change the following sentences into passive voice. 1. You should finish the work before you leave. _________________________________________________.Bottom of Form 2. You can serve this wine with chicken or fish. _________________________________________________Bottom of Form 3. Bottom of ForBottom of ForBottom of FormWe will elect a new government next year. _________________________________________________Bottom of ForBottom of Form 4. They might give him an award. _________________________________________________Bottom of Form 5. You must give students enough time to finish. _________________________________________________. 6. You should keep flowers in a warm sunny place. ________________________________________________. 7. Nobody can solve the mystery. __________________________________________________. 8. You should have fasten the seat belt when you traveled by car yesterday. ____________________________________________________ 9. They needn’t have bought bread because we have a lot on the table. _________________________________________________________ 10. Will the teacher test our English? _________________________________________________________
Câu 1: Tính nhanh(nếu có thể) a) 29 + 140 + 71 b) 17.2016+2016.83 c) 75 : 73 – 343 : 7 d) e) f) Câu 2: Tìm x biết: a) (x – 39) + 21 = 32 b) 60 : (5 – x) = 20 c) 3.(x + 2) - 8 = 46: 44 d) 1 + 2 +…+ x = 45 e) 2x – 49 = 45 f) 145 – (x + 26) = 97
mọi người ơi cứu!! cho biết 2 đại lượng x và y tỉ lệ thuận vs nhau và khi x = -5 thì y= 1/2 . Khi y =5 thì giá trị tương ứng của x là : A :50 B :1/50 C: -50 D: -1/50
Giúp mình 3 bài tự luận hoá vs ạ
Thế nào là từ láy toàn bộ từ láy bộ phận
Giúp mình với mình cần gấp câu 2 ạ
B= 1/3x^2y+xy^2-xy+1/2xy^2-5xy-1/3x^2y Thu gọn đa thức sau
giúp mình bài 3 với nha các bạn
Choose the word or phrase among A, B, C, or D that best fits the blank space in the following passage. Maple Tree Trees have ………………….. (1) a meaningful role in the ………………….. (2) development of Canada and continue to be of commercial, environmental and aesthetic importance to all Canadians. Maples contribute valuable wood products, keep the maple sugar ………………….. (3) alive and have to beautify the landscape. Since 1965 the maple leaf ………………….. (4) the most important feature of the National Flag of Canada and the Maple three with the leaves has become the most well-known Canadian ………………….. (5) and nationally and internationally. Maple leaf pins and badges are proudly ………………….. (6) by Canadians abroad, and are recognised around the world. ………………….. (7) the maple leaf is closely associated with Canada, the map tree was never officially recognize ………………….. (8) Canada's emblem until 1966. 1. A. taken B. given C. done D. played 2. A. history B. historical C. historic D. historian 3. A. industry B. industries C. industrial D. industrially 4. A. was B. have been C. has been D. is 5. A. sign B. symbol C. tree D. leaf 6. A. wear B. wore C. worn D. to be worn 7. A. Because B. So C. But D. Although 8. A. of B. with C. as D. for
Loga.vn - Cộng Đồng Luyện Thi Trực Tuyến
