PP數學

[cutefox0108]

if Xis equal to the sum of the even integers from 40 to 60,in clusive,and y is the number of even integers from 40 to 60 ,inclusive ,what is the value of X+Y?

A. 550
B. 551
C. 560
D. 561
E. 572

答案D
我算X連加偶數就已經 550
再加Y為40~60整數,應該至考都會超過550+40 =590

請問大家幫我解答好嗎

[麥香寶]

題目y是指 40~60的偶數數目
所以 y=11 (40,42,44,46...58,60 共11個)

x+y= 550+11=561

[cutefox0108]

If n denotes a number to the left of 0 on the number line such that he square of n is less than 1/100, then the reciprocal of n must be
A less than -10
B between -1 and -1/10
C between -1/10 and –
D between 0 and 1/10
E greater than 10

[cutefox0108]

忘了寫答案是A

我認為答案是C耶~若是1/100代表n=-1/10
相對應的數應該就是0~1/10

麻煩了

[cutefox0108]

題目y是指 40~60的偶數數目
所以 y=11 (40,42,44,46...58,60 共11個)

x+y= 550+11=561

原來是英文問題~~謝謝您的回答!!
太感激了

[麥香寶]

題目是問 n的倒數 (the reciprocal of n)

[Ivy-Canada]

題目是問 n的倒數 (the reciprocal of n)

請問一下reciprocal 只是分子分母倒過來嗎? 還是正負也要倒過來? for example: if n=-1/10, the receiprocal of n 是 -10 還是10?

[dibert8]

If n denotes a number to the left of 0 on the number line such that he square of n is less than 1/100, then the reciprocal of n must be
A less than -10
B between -1 and -1/10
C between -1/10 and –
D between 0 and 1/10
E greater than 10

-1/10 < n < 0 => 1/n < -10

[dibert8]

請問一下reciprocal 只是分子分母倒過來嗎? 還是正負也要倒過來?

只是分子分母倒過來.