Maths 6
Q5:
If b, c, and d are constants and x2 + bx + c = (x + d)2 for all values of x, what is the value of c?
(1) d = 3
(2) b = 6 此题选（1）不对吗？当d=3时，x2 + bx + c = x
2 +2dx+9,可知c=9。可标注答案是d,?
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer:D
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Q9:
If the average (arithmetic mean) of four different numbers is 30, how many of the numbers are greater than 30?
(1) None of the four numbers is greater than 60.
(2) Two
of the four numbers are 9 and 10, respectively.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
这道题我选错了，我觉得2可以单独回答提问。4个数的平均数等于30，且有两个已知并小于30，那另外两个一定大于30了。为什么选c呢？？
Answer: C
Q27:
The sum of positive integers x and y is 77. What is the value of xy?
(1) x = y + 1
(2) x and y have the same tens digit.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
这里（2）中，x,y有相同的十位数有很多，如（31，36），（32，35），（33，34），都满足x+y=77,答案为什么是d呢？？
Answer:D
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Q33:
A salesperson received a 6-percent commission on the amount of total sales up to and including $10,000, and an r-percent commission on the amount of total sales over $10,000. If the salesperson received a total commission of $920 on total sales of $14,000, what was the value of r?
A. 3.2
B. 4.3
C. 6.6
D. 8.0
E. 9.2
这题是啥意思？？Answer: D
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MATHE7
Q3:
Material A costs $3 per kilogram, and material B costs $5 per kilogram. If 10 kilograms of material K consists of x kilograms of material A and y kilograms of material B, is x > y?
(1) y > 4
(2) The cost of the 10 kilograms of material K is less than $40.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient
从（2）中怎么得出答案的？？Answer: B
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Q13:
What is the value of the integer n?
(1) n(n + 2) = 15
(2) (n + 2)n = 125
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.答案是b,k可我觉得（1）也能算出n=3呀，Answer:B
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Q28:
This year Henry will save a certain amount of his income, and he will spend the rest. Next year Henry will have no income, but for each dollar that he saves this year, he will have 1 + r dollars available to spend. In terms of r, what fraction of his income should Henry save this year so that next year the amount he was available to spend will be equal to half the amount that he spends this year?
Answer: E这体看不懂，谁能帮翻一下，谢谢啊！
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Q36:
What is the sum of a certain pair of consecutive odd integers?
(1) At least one of the integers is negative.
(2) At least one of the integers is positive.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
为什么选Answer: C？
If b, c, and d are constants and x2 + bx + c = (x + d)2 for all values of x, what is the value of c?
(1) d = 3
(2) b = 6
选D啊,没错
解(2)x^2+bx+c=x^2+2dx+d^2
if b=6 2d=6 d=3
then c=d2 c=9
6-33我也想问...
Q5 b=6 because 2xd=bx d=3 => c=3 both statement alone are sufficient
Q9 for ex the four number is 9,10,11 90 respectively, so 2) alone is unsufficient
Q27 只有38，39这种可能
Q33 6%*10000+r%*(14000-10000)=920 r=8
Q3 A:x+y=10 B:3x+5y<40 Change equation A to 3x+3y=30 along with equation B => 2y<10 => y<5 so x>5 x>y
Q13 n^2+2n-15=0 (n+5)*(n-3)=0 so n has two value
Q28 This year Henry will save a certain amount of his income, and he will spend the rest. Next year Henry will have no income, but for each dollar that he saves this year, he will have 1 + r dollars available to spend. In terms of r, what fraction of his income should Henry save this year so that next year the amount he was available to spend will be equal to half the amount that he spends this year?
翻译：今年H会省下一部分收入，其余得花掉。第二年H将没有收入，但是今年他每省一块钱，第二年就有1＋r块钱用。H今年省下多少比例的收入可以使得第二年他可以用的钱是今年的一半，用含有r的式子来表示
Q36 只有当两个条件都存在时 该两个奇数的和为零，仅有条件一 ex -3 -1或者 -3 -5和是不一样的，另一条件通理
太感谢了！这么精彩的答案！有些题是不是很可笑？可当时就是转不过弯，没办法！！谢谢！
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