Re: [計量] PP1-DS-64.180.192.198&PS63~~
※ 引述《haby (haby)》之銘言:
: 63.
: For which of the following functions is f(a + b) = f(a) + f(b) for all
: positive numbers a and b ?
: (A) f(x) = x^2
: (B) f(x) = x + 1
: (C) f(x) = 根號2
: (D) f(x) = 2/x
: (E) f(x) = -3x
: 答案E 這種類的題目要怎麼解呢@@~~
這個題目用代的好了
題目說 f(a+b)=f(a)+f(b)
A.f(a+b)=(a+b)^2=a^2+b^2+2ab f(a)=a^2,f(b)=b^2 不選 差了2ab這項
B.f(a+b)=a+b+1 f(a)=a+1,f(b)=b+1 不選 差1
C.不管什麼都是根號2 相加會變成 2跟號2 不選
D.f(a+b)=2/(a+b) f(a)+f(b)=2/a+2/b=(2a+2b)/ab
E.f(a+b)=-3(a+b) f(a)+f(b)=(-3a)+(-3b)
選E
: 64.
: Are at least 10 percent of the people in Country X who are 65 years old or
: older employed?
: (1) In Country X, 11.3 percent of the population is 65 years old or older.
: (2) In Country X, of the population 65 years old or older, 20 percent of the
: men and 10 percent of the women are employed.
: 答案B
題目問是不是至少有10%的人口是 65歲以上(含)有工作的
(1)不知道工作
(2)在65歲以上(含) 有20%m,10%f是有工作的
題目問的是有沒有大於等於10%(f+m)
可以算選Bꔊ
: 180.
: Are x and y both positive?
: (1)2X-2Y=1
: (2)X/Y>1
: 答案C
(1)2(x-y)=1
(2) 考慮正負關係
若y>0 則x>y
若y<0 則x<y(乘負號 不等式換方向)
合併
y>0 代入(1) 2(x-y)=1 兩個都是正數
y<0 代入(1) 不合 x<y
因為2(x-y)=1 會小於0
選c
: 192.
: Of the 75 houses in a certain community, 48 have a patio. How many of the
: houses in the community have a swimming pool?
: (1) 38 of the houses in the community have a patio but do not have a swimming
: pool.
: (2) The number of houses in the community that have a patio and a swimming pool
: is equal to the number of houses in the community that have neither a
: swimming pool nor a patio.
: 答案B 我選C 囧> 要怎麼只看第二個選項推得呢??
(2)兩個都有=兩個都沒有 設為N
原題問S多少
P+S-N+N=75
S=27
(題目是說這75間房子 P有48,S不知 但也有兩個同時有的 或兩個同時沒有的)
所以得到上面式子 畫圖也行
選B
: 198.
: Did one of the 3 members of a certain team sell at least 2 raffle tickets
: yesterday?
: (1) The 3 members sold a total of 6 raffle tickets yesterday.
: (2) No 2 of the members sold the same number of raffle tickets yesterday.
: 答案D 恩恩 不太懂第二個選項@@~~
: 麻煩好心人解答 感恩^^
(1)全部賣出6 一定會有大於2的
(2)沒有任何兩人是賣相同數目的
也就是說 假設有一個賣0 其他兩個賣1,2 這是最小可能
選D
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