Recent questions tagged cat2019-2

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48
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57
How many pairs $(m,n)$ of positive integers satisfy the equation $m^{2}+105=n^{2}$ _______
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60
If x is a real number, then $\sqrt{\log _{e}\frac{4x-x^{2}}{3}}$ is a real number if and only if$1\leq x\leq 2$$-3\leq x\leq 3$$1\leq x\leq 3$$-1\leq x\leq 3$
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The average of $30$ integers is $5$. Among these $30$ integers, there are exactly $20$ which do not exceed $5$. What is the highest possible value of the average of these...
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66
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68
In a triangle $\text{ABC}$, medians $\text{AD}$ and $\text{BE}$ are perpendicular to each other, and have lengths $12$ cm and $9$ cm, respectively. Then, the area of tria...
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69
Let $a_{1},a_{2}\dots$ be integers such that $a_{1}-a_{2}+a_{3}-a_{4}+\dots+(-1)^{n-1}a_{n}=n$, for all $n\geq 1$ Then $a_{51}+a_{52}+\dots+a_{1023}$ equals$-1$$10$$0$$1$...
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70
The real root of the equation $2^{6x}+2^{3x+2}-21=0$ is$\frac{\log_{2}7}{3}$$\log_{2}9$$\frac{\log_{2}3}{3}$$\log_{2}27$
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71
The quadratic equation $x^{2}+bx+c=0$ has two roots $4a$ and $3a$, where a is an integer. Which of the following is a possible value of $b^{2}+c$?$3721$$549$$427$$361$
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75
How many factors $2^{4}\times3^{5}\times10^{4}$ are perfect squares which are greater than $1$ _______
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76
Let $a,b,x,y$ be real numbers such that $a^{2}+b^{2}=25,x^{2}+y^{2}=169$, and $ax+by=65$. If $k=ay-bx$, then$k=0$$0< k\leq \frac{5}{13}$$k=\frac{5}{13}$$k \frac{5}{13}$
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77
What is the largest positive integer $n$ such that $\frac{n^{2}+7n+12}{n^{2}-n-12}$ is also a positive integer?$8$$12$$16$$6$
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79