nonnnn

phân tích đa thức thành nhân tử : 4(x^2+50+15x)(x^2+18x+72)-3x^2

tìm x biết:     x^3-x^2-11x+4=0 

(1-4/9)(1-4/25)(1-4/49)(1-4/81).....(1-4/(2n+1)²)

Bài 3: Cho a; b; c là ba cạnh của 1 tam giác .CMR:
(a+b+c)^2+(a-b+c)^2>4b^2

viết đoạn văn khoảng 12 câu theo phép lập luận diễn dịch/ quy nạp để làm rõ cái chết của chú bé lượm trong bài thơ lượm của tố hữu

Biết x+1/x=5 .Tính x⁴+1/x⁴

Read the following passage and choose the correct answer.

We use many different energy sources to do work for us. Energy sources are classified into two groups - renewable and nonrenewable. Non-renewable energy sources are those that take millions of years to form and will run out some day. It is energy that comes from fossil fuels such as coal, crude oil, and natural gas. Fossil fuels are mainly made up of carbon and were formed millions of years ago. The chemical reaction which takes place when we burn fossil fuels releases carbon compounds such as carbon monoxide and carbon dioxide into the air. Carbon dioxide is one of the green house gases which is contributing to global warming and air pollution. On the other hand, renewable energy sources will never run out, are better for the environment and do not cause pollution. Renewable energy is often called green energy because it is a natural energy, always available and does not have to be formed like nonrenewable energy. The green energy is always there. For example, the Sun consistently shines, water is abundant, and the winds blow throughout the year. The five types include solar, energy from the Sun; geothermal, energy from heat within the Earth; hydroelectric, energy from moving water; biomass, energy from dead plants and microorganisms and finally, energy from the wind.

36. Which sentence is NOT TRUE about non-renewable energy sources?

A. They take millions of years to form. B. They will run out someday C. They come from fossil fuels D. they are always available

37. Which sentence is TRUE about renewable energy sources?

A. They are bad for the environment B. They are not always available C. They are called green energy D. They can be used up

38. When does the chemical reaction take place?

A. When we use energy from the wind. B. When we burn fossil fuels C. When we use green energy D. When global warming happens

39. What is NOT INCLUDED in the five types of green energy?

A. solar B. hydroelectric C. natural gas D. biomass

40. What does geothermal come from?

A. dead plants B. heat within the earth C. the wind D. moving water

Có bao nhiêu cặp số nguyên (x;y) thỏa mãn 5y – 3x = 2xy – 11

Câu 11: [VDC] Cho đa thức f(x) = ax² + bx + c thỏa mãn 13a + b + 2c = 0. Hãy chọn
phát biểu ĐÚNG
A. f(– 2). f(3) ≤ 0 B. f(– 2). f(3) > 0
C. f(−2) < f(3)      D. f(−2) > f(3)