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English Senior High

空欄Aのとこなんですけど選択肢にwhereasとyetがあってその二つの違いがわかんないです 早稲田教育英語2012の大問2です

from injuries due to falls. Poor vision accounts for 18 percent of broken hips. So, why don't more people get regular eye exams? For one thing, eye exams in the United States are not covered by public nor by many private health insurers. Even the new U.S. health care law has yet to include basic eye exams and rehabilitation services for vision loss, though advocates are pushing hard for this coverage in regulations now being prepared. But even those who have insurance or can pay out of pocket are often reluctant to go for regular eye exams. Fear and depression are common impediments for those at risk of vision loss. Patients worry that they could become totally blind and unable to go partying, read or drive a car, he said. [A] many people fail to realize that early detection can result[] vision-preserving therapy. Those at risk include people with diabetes, high blood pressure, high cholesterol or cardiovascular disease, as well as anyone who has been a smoker or has a family history of an eye disorder like macular degeneration, diabetic retinopathy or glaucoma. The eyes are truly a window to the body, and a proper eye exam can often alert physicians to a serious underlying disease like diabetes, multiple sclerosis or even a brain tumor. Mr. Lovett recommends that all children have "a professional eye exam" before they start elementary school. "Being able to read the eye chart, which tests distance vision, is not enough, since most learning dhe is whild de adequate

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Mathematics Senior High

(2)の解説お願いします。

52 00000 不等式が常に成り立つ条件 (絶対不等式) 0 基本例題 91 〔東京電機大] (1) すべての実数xについて, 不等式 x2ax+2a> 0 が成り立つように、 定数aの値の範囲を定めよ。 p.14 基本事項 (2) すべての実数xに対して, 不等式 kx2+(k+1)x+k ≦0 が成り立つよう な定数kの値の範囲を求めよ。 CHART & SOLUTION 定符号の2次式 常に ax2+bx+c>0⇔a> 0, D < 0 常に ax²+bx+c≦0 a<0, D≦0 (1) x2の係数は1>0 → D<0であるαの条件を求める。 (2) 単に「不等式」とあるから,k=0 の場合(2次不等式でない場合)も考えることに注意。 k0 の場合、 < 0 かつ D≦0 であるんの条件を求める。 解答 (1) x²-ax+2a=0 の判別式をDとする。 x2の係数は正であるから、常に不等式が成り立つ条件は D<0 ここで D=(-α)²-4・1・2a=a²-8a=a(a−8) D< 0 から 求めるαの値の範囲は (2) kx2+(k+1)x+k≦0: ① とする。 [1] k=0 のとき, ① は x≤0 これはすべての実数xに対しては成り立たない。 [2] k≠0 のとき, 2次方程式 kx2+(k+1)x+k=0 の判 別式をDとすると, すべての実数x に対して, ① が成 り立つための条件は ん < 0 かつ D≦0 ここで D=(k+1)²-4・k・k=-3k2+2k +1 D≦0から よって -(3k+1)(k-1) (3k+1)(k-1)≧0 1≤k == k≦- 0<a<8 243h 3' <0 との共通範囲をとると ks--1/32 以上から 求めるんの値の範囲は R≤ - 1²/13 下に凸の放物線が常に x軸より上側にあるた めの条件と同じ(p.14 基本事項 2 参照)。 ( 下に凸 D<0 FRER > (2) [2] 上に凸の放物線 x軸と共有点をもたら い,または,x軸と接す ある条件と同じ。 [2] I 上に凸 D≤0

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