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190321
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$$(x+y)^2-(x-y)^2=27$$.xy=?
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190321
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$$a_1=45$$,$$a_2=49$$,$$a_n=a_{n-2}+7(n \geq 3) $$. Which of the following option is in the sequence{$$a_n$$} ?
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190321
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After someone deposited r dollars in his account, the balance was t dollars. Then, he spent a third of his balance on purchases. How much was the balance of his account after consumption?
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190321
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Is $$x^4
1:$$x^4
2.$$x^3 < y^4$$
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190321
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In a rectangular coordinate system, lines r and h both pass through the point (1,-1). The product of the slope of line r and line h is -1. The x-intercept of line r is 3. What is the coordinate of the intersection of line h with the x-axis?
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190321
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x,y are positive integers. x>y. Is $$x^{y-1}$$ odd?
1: x-y is even.
2: x+y is even.
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190321
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The cost of each table is $50. The cost of each chair is $5. The profit of the table is 30% of the cost. The profit of the chair is 50% of the cost. A furniture store sold five times as many chairs as tables. The total profit on tables and chairs was $550. What's the total cost price of the tables and chairs sold?
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190321
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The slopes of lines $$l_1$$ and $$l_2$$ are larger than 0. The y-intersection of both lines are larger than 0. Is the x-intersection of $$l_1$$ larger than that of $$l_2$$?
1: The y-intersection of $$l_1$$ is larger than that of $$l_2$$.
2: The slope of $$l_1$$ is smaller than that of $$l_2$$.
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190321
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p=10k+1. k is a positive integer. What's the unit digit of $$(p^2)^100$$?
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190321
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x@y=$$x^2y+xy^2-xy$$.(5@3)+(3@5)=?
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190321
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How many of the 500 numbers from 1 to 500 have a remainder of 1 when divided by 7, and a remainder of 2 when divided by 3?
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190321
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In the cuboid ABCD-EFGH, AB=13, AD=12, AE=10. AG=?
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190415
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As shown in the figure, there are two semicircles and one circle in rectangle ABCD. The whole circle is tangent to two semicircles. The square EFGH is inscribed to the circle. What is the area of the shaded area?
1: EF=2
2: The area of ABCD is 16.
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190321
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The line whose algebraic expression is f(x)=kx+b goes through the point (0,1). f(1)=？
1: f(3)-f(2)=8
2: f(7)=57
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190321
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Is 3n(n+1) an even number?
1: n is even.
2: $$n^2-1$$ is even.
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190415 还原机经选题: 数论&代数
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a,b,c,d are integers. 1 ≤ a,b,c,d ≤ 9.(a+d)(b+c)=?
1：abcd+dcba=7557.
2：abcd+ dba =1957
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190321
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What's the greatest prime factor of $$5^{500}+5^{501}+5^{502}$$?
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190415
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$$S_2$$+$$S_8$$=?
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190321
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Is there a solution to the equation ax^2+bx+c=0?
1：a>b
2：b>1/2
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190321
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Regular hexagon ABCDEF is inscribed on circle O whose radius is 5. What is the area of the shaded area?
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