求指教几道数学，3Q

天津lbsh1990

A certain roller coaster has 3 cars, and a passenger is equally likely to ride in any 1 of the 3 cars each time that passenger rides the roller coaster.If a certain passenger is to ride the roller coaster 3 times, what is the probability that the passenger will ride in each of the 3 cars?



A.0

B.1/9

C.2/9

D.1/3

E.1
题目不是太理解


If 10⁵⁰ – 74 is written as an integer in base 10 notation, what is the sum of the digits in that integer?



A.424

B.433

C.440

D.449

E.467

If x > 0, then 1/[√(2x)+√x] =



A.1/√(3x)

B.1/[2√(2x)]

C.1/(x√2)

D.(√2-1)/√x

E.(1+√2)/√x

v是啥意思

A positive integer n is said to be “prime-saturated” if the product of all the different positive prime factors of n is less than the square root of n.What is the greatest two-digit prime-saturated integer?



A.99

B.98

C.97

D.96

E.95

没大读懂题


If 10⁵⁰ – 74 is written as an integer in base 10 notation, what is the sum of the digits in that integer?



A.424

B.433

C.440

D.449

E.467

If x > 0, then 1/[√(2x)+√x] =



A.1/√(3x)

B.1/[2√(2x)]

C.1/(x√2)

D.(√2-1)/√x

E.(1+√2)/√x

v是啥意思

沐爽

1    E 2/9     （ 3!/3³）
2    C 440    （9×48+2+6）
3    D （是根号。。。。）
4    D 96（ 96=2^5×3  (2X3)^2=36<96 选D）
应该是这样吧

天津lbsh1990

第一道题可不可以这样理解，一个人乘roller coaster（roller coaster有三个车厢）三次，问每次乘坐不同车厢的概率？
还有，最后一道能不能解释的清楚点，谢谢！

沐爽

1 就是这个意思吧
4 就是分解质因子
A 99=3^2x11     (3x11)^2=33^2>99 不符合
B 98=2x7^2       (2x7)^2=14^2>98 不符合
C 97=97             97^2>97
选d

斯坦福桥的车夫

能具体解释一下第二题吗？谢谢

clairesslc

CCDC
10的50次方就是1后面50个0 ，减去74，最后两位是26，前面有48个9,所以和就是48*9+6+2=440