Tìm a để phương trình  a^2 (x-3)=2(2a-1)-5a +x vô nghiệm 

     Jupiter is the largest and most massive planet and is fifth in order of distance from the sun. It is well placed for observation for several months in every year and on average is the brightest of the planets apart from Venus, though for relatively brief periods Mars may outshine it. Jupiter's less than 10 hour rotation period gives it the shortest day in the solar system in so far as the principal planets are concerned. There are no true seasons on Jupiter because the axial inclination to the perpendicular of the orbital plane is only just over 3°-less than that for any other planet.

     The most famous mark on Jupiter is the Great Red Spot. It has shown variations in both intensity and color, and at times it has been invisible, but it always returns after a few years. At its greatest extent it may be 40,000 kilometers long and 14,000 kilometers wide, so its surface area is greater than that of Earth. Though the latitude of the Red Spot varies little, it drifts about in longitude. Over the past century the total longitudinal drift has amounted to approximately 1200°. The latitude is generally very close to -22°. It was once thought that the Red Spot might be a solid or semisolid body floating in Jupiter's outer gas. However, the Pioneer and Voyager results have refuted that idea and proven the Red Spot to be a phenomenon of Jovian meteorology. Its longevity may well due to its exceptional size, but there are signs that it is decreasing in size, and it may not be permanent. Several smaller red spots have been seen occasionally but have not lasted.

Question 36: It can be inferred from the passage that …………………….

     A. a day on Earth is shorter than a day on Jupiter

     B. there are other structures on Jupiter that has the same size as the Great Red Spot

     C. there are times when Great Red Spot cannot be observed from the earth

     D. the Great Red Spot is the only structure on Jupiter

Question 37: According to the passage, which planet typically shines the most brightly?

     A. Earth                    B. Jupiter                       C. Venus                      D. Mars

Question 38: According to the passage, the Great Red Spot …………………...

     A. has different colors                                              

     B. is as big as the earth

     C. is a solid structure floating in the air 

     D. has increased its size over the years

Question 39: The word "it” in paragraph 2 refers to ………………………….

     A. Jupiter             B. The Great Red Spot            C. intensity              D. color

Question 40: The word "exceptional" in paragraph 2 mostly means …………..

     A. extreme              B. sustainable             C. temporary              D. infrequent

Question 41: According to the passage, which of the following is NOT true?

     A. Jupiter is bigger than all the other planets in the solar system.

     B. A day in Jupiter is nearly 10 hours long.

     C. The Red Great Spot moves more vertically than horizontally.

     D. Scientists have proof showing that smaller red spots are increasing their size to become other Great Red Spots.

Question 42: The passage was probably taken from ………………………..

     A. an art journal                                                    B. a geology magazine

     C. a high school textbook                                     D. an archaeology book

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

Question 43: The ocean probably distinguishes the earth from other planets of the solar system, for scientists believe that large bodies of water are not existing on the other planets.

     A. from                  B. probably                  C. for                  D. are not existing

Question 44: In many places in the world, social or religious restrictions which prevent women from travelling freely.

     A. in                     B. religious                      C. which                      D. freely

Question 45: Halley’s comet, viewing through a telescope, was quite impressive.

     A. viewing                 B. through                   C. quite                 D. impressive

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

Question 46: Had the advertisement for our product been better, more people would have bought it.

     A. Not many people bought our product because it was so bad.

     B. Our product was of better quality so that more people would buy it.

     C. Fewer people bought our product due to its bad quality.

     D. Since the advertisement for our product was so bad, fewer people bought it.

Question 47: "How beautiful you are today!” he said.

     A. He complimented her on being beautiful today.

     B. He said to me that she was beautiful that day.

     C. He complimented her on being beautiful that day.

     D. He complemented her on being beautiful that day.

Question 48: The sooner we solve this problem, the better it will be for all concerned.

     A. If all concerned are better, we can solve this problem soon.

     B. If we could solve this problem soon, it would be better for all concerned.

     C. If we can solve this problem soon, it will be better for all concerned.

     D. It would be better for all concerned if we can solve this problem soon.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each of sentences in the following questions.

Question 49: Farmers depend on meteorologists. They need meteorologists' accurate forecasts for successful agricultural planning.

     A. Due to meteorologists’ accurate forecasts, farmers depend on them for successful agricultural planning.

     B. Farmers depend on meteorologists who need their accurate forecasts for successful agricultural planning.

     C. Farmers need meteorologists’ accurate forecasts for successful agricultural planning and so they depend on you.

     D. Farmers depend on meteorologists, whose accurate forecasts they need for successful agricultural planning.

Question 50: Their dog was very fierce. People didn’t dare to come up to their house.

     A. If their dog were not fierce no one would visit their house.

     B. Their dog was not fierce enough for people visit their house.

     C. They had such a fierce dog so that people didn't dare to come up to their house.

     D. They had so fierce a dog that no-one dared come up to their house

Hình thang cân ABCD có đáy nhỏ AB; đường cao AH. Biết
AH=6cm; AC=10cm .M; N lần lượt là trung điểm của AD và BC.
a) CMR: MN=HC
b) Tính SABCD?