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English Senior High

英語の長文です。 文法表現のあるところが知りたいです。 よろしくお願いします。

UNIT 1 5 Reading Passage 10 15 20 20 25 Listening There are more than 37,000 known species of spiders in the world in a wide variety of shape's and sizes! The largest spiders in the world live in the rain forests of South America and are known by the people who live there as the "bird-eating spiders." These spiders can grow up to 28 centimeters in length- about the size of a dinner plate, and, as their name suggests, have been known to eat small birds. In comparison, the smallest species of spider in the world is native to Western Samoa. These tiny spiders are less than half a millimeter long — about the size of a period on this page and live in plants that grow on mountain rocks. - Some people like to keep spiders as pets, particularly tarantulas, which are native to North America and can live for up to twenty-five years, Most people, on the other hand, do not like touching spiders, and a significant number of people are afraid of them, mainly because of their poison. However, despite their bad reputation, only thirty of the 37,000 known species of spiders are deadly to humans. Spiders actually provide benefits to humans, by catching and eating harmful insects such as flies and mosquitoes. - - The main thing that makes spiders different from other animals is that they spin web's to catch the small insects they feed on. The unique silk of a spider's web is produced by special organs found spider web is five times in the lower part of the spider's body. It is light, elastic, and strong stronger than steel. Additionally, it is completely biodegradable. This means that the web will making it perfect for uses completely decompose¹ and eventually return to nature over time such as making fishing nets. Some people have tried to raise spiders commercially in order to collect the silk these spiders produce, but no one has ever really managed to make a go of it. One reason why these businesses never stand a chance is because it takes 670,000 spiders to produce half a kilogram of silk, and all of these spiders need living insects for their food. In addition, spiders are usually solitary² animals, and need to be kept alone. Researchers at an American company working together with two U.S. universities may have found a solution to making artificial spider web. Using genetically modified silkworms,³ the company hopes that in the long run it will be able to make large quantities of very light, very strong fiber for medical as well as other uses. Additionally, because the manufacture of the artificial web is from living silkworms, the industry potentially would be non-polluting and less harmful to the environment

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Mathematics Senior High

高校数学の問題です。 ( 1)を判別式で解いたのですが 答えの範囲が出てきませんでした。 判別式で解く方法で教えてください。

実戦問題 13 2次方程式の解の存在範囲 mを定数として, 2次方程式x+2(m+2)x+2m+12 = 0... ① について考える。友 (2) 方程式 ①が2より大きい解と2より小さい解を1つずつもつとき, m の値の範囲は m<オカである。 (1)方程式 ①が異なる2つの正の解をもつときの値の範囲は アイ <m< ウエ である。 (3) 方程式 ①が1と2の間、2と3の間にそれぞれ解を1つずつもつとき,mの値の範囲は 解答 (1) f(x)=x+2(m+2)x+2m +12 とおくと f(x) = {x+(m+2)}2-(m+2)^+2m+12 =(x+m+2)-m²-2m+8 @ 方程式 ①が異なる2つの正の解をもつとき, y = f(x) のグラフは次 の (i)~ (iii) を満たす。 キクケ コ <<サシ y=f(x)のグラフは頂点が (-m-2, -m²-2m+8) であり、下に凸の放物線であ ( f (1 Key 1 (i) x軸と異なる2点で交わる。 y=f(x) (不 (ii) 軸が x > 0 の部分にある。 (iii) f(0) > 0 (i)より, 頂点のy座標は負であるから m²-2m+8< 0 0 f(0) 2次方程式 ① の判別式を考え O x D -m-2 4 = (m+2)² − (2m+12) > よって,m²+2m-80より (-2)(+4)>0 としてもよい。 ゆえに m<-4, 2<m (ii)より, 軸について x=-m-2> 0 ゆえに m<-2 C (Ⅲ)より,f(0) =2m+120 であるから m>-6 (i) ~ (Ⅲ)より, 求めるmの値の範囲は -6<m<-4 (-6-4-2 2 m (2) 方程式①が2より大きい解と2より小さい解をもつとき,y=f(x) y=f(x) のグラフは下に凸 Key 1 のグラフはf(2) を満たす。 f(2) = 6m+24 < 0 ゆえに m<-4 y y=f(x) 放物線であるから, f (2) <0 満たせば、必然的にx>2 範囲とx<2の範囲のそれ れにおいて, 1度ずつx軸と わる。 Key (3) 方程式 ①が1と2の間,2と3の間にそれぞれ 解を1つずつもつとき,y=f(x) のグラフは次 の (iv) ~ (vi) を満たす。 (iv) f (1) > 0 (v) f(2) <0 (vi) f(3)>0 (iv) より f(1) = 4m+170 であるから (v)よりf(2)=6m+24< 0 であるから 17 m>- 4 (vi) よりf(3) = 8m+33> 0 であるから (iv)~ (vi) より, 求めるmの値の範囲は - m <-4 攻略のカギ! y=f(x) 2 1 3 x m>- 388 33 33 <m<4 17 33

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