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1964 AMC 12

Question 1

What is the value of $\left[\log_{10}\left(5\log_{10}100\right)\right]^2?$
  1. $\log_{10}50$
  2. $25$
  3. $10$
  4. $2$
  5. $1$

Question 2

The graph of $x^2-4y^2=0$ is:
  1. a parabola
  2. an ellipse
  3. a pair of straight lines
  4. a point
  5. none of these

Question 3

When a positive integer $x$ is divided by a positive integer $y,$ the quotient is $u$ and the remainder is $v,$ where $u$ and $v$ are integers. What is the remainder when $x+2uy$ is divided by $y?$
  1. $0$
  2. $2u$
  3. $3u$
  4. $v$
  5. $2v$

Question 4

The expression

$$
\frac{P+Q}{P-Q}-\frac{P-Q}{P+Q},
$$

where $P=x+y$ and $Q=x-y,$ is equivalent to:
  1. $\dfrac{x^2-y^2}{xy}$
  2. $\dfrac{x^2-y^2}{2xy}$
  3. $1$
  4. $\dfrac{x^2+y^2}{xy}$
  5. $\dfrac{x^2+y^2}{2xy}$

Question 5

If $y$ varies directly as $x,$ and if $y=8$ when $x=4,$ the value of $y$ when $x=-8$ is:
  1. $-16$
  2. $-4$
  3. $-2$
  4. $4k,$ $k=\pm1,$ $\pm2,$ $\ldots$
  5. $16k,$ $k=\pm1,$ $\pm2,$ $\ldots$

Question 6

If $x,$ $2x+2,$ $3x+3,$ $\ldots$ are in geometric progression, the fourth term is:
  1. $-27$
  2. $-13\dfrac12$
  3. $12$
  4. $13\dfrac12$
  5. $27$

Question 7

Let $n$ be the number of real values of $p$ for which the roots of

$$
x^2-px+p=0
$$

are equal. Then $n$ equals:
  1. $0$
  2. $1$
  3. $2$
  4. a finite number greater than $2$
  5. an infinitely large number

Question 8

The smaller root of the equation

$$
\begin{aligned} &\left(x-\frac34\right)\left(x-\frac34\right)\\ &\quad+\left(x-\frac34\right) \left(x-\frac12\right)=0 \end{aligned}
$$

is:
  1. $-\dfrac34$
  2. $\dfrac12$
  3. $\dfrac58$
  4. $\dfrac34$
  5. $1$

Question 9

A jobber buys an article at $\$24$ less $12\dfrac12\%.$ He then wishes to sell the article at a gain of $33\dfrac13\%$ of his cost after allowing a $20\%$ discount on his marked price. At what price, in dollars, should the article be marked?
  1. $25.20$
  2. $30.00$
  3. $33.60$
  4. $40.00$
  5. none of these

Question 10

Given a square with side of length $s.$ On a diagonal as base a triangle with three unequal sides is constructed so that its area equals that of the square. The length of the altitude drawn to the base is:
  1. $s\sqrt2$
  2. $\dfrac{s}{\sqrt2}$
  3. $2s$
  4. $2\sqrt{s}$
  5. $\dfrac2{\sqrt{s}}$

Question 11

Given $2^x=8^{y+1}$ and $9^y=3^{x-9},$ find the value of $x+y.$
  1. $18$
  2. $21$
  3. $24$
  4. $27$
  5. $30$

Question 12

Which of the following is the negation of the statement: For all $x$ of a certain set, $x^2\gt0?$
  1. For all $x,$ $x^2\lt0$
  2. For all $x,$ $x^2\leq0$
  3. For no $x,$ $x^2\gt0$
  4. For some $x,$ $x^2\gt0$
  5. For some $x,$ $x^2\leq0$

Question 13

A circle is inscribed in a triangle with side lengths $8,$ $13,$ and $17.$ Let the segments of the side of length $8,$ made by a point of tangency, be $r$ and $s,$ with $r\lt s.$ What is the ratio $r:s?$
  1. $1:3$
  2. $2:5$
  3. $1:2$
  4. $2:3$
  5. $3:4$

Question 14

A farmer bought $749$ sheep. He sold $700$ of them for the price paid for the $749$ sheep. The remaining $49$ sheep were sold at the same price per head as the other $700.$ Based on the cost, the percent gain on the entire transaction is:
  1. $6.5$
  2. $6.75$
  3. $7$
  4. $7.5$
  5. $8$

Question 15

A line through the point $(-a,0)$ cuts from the second quadrant a triangular region with area $T.$ The equation of the line is:
  1. $2Tx+a^2y+2aT=0$
  2. $2Tx-a^2y+2aT=0$
  3. $2Tx+a^2y-2aT=0$
  4. $2Tx-a^2y-2aT=0$
  5. none of these

Question 16

Let $f(x)=x^2+3x+2$ and let $S$ be the set of integers $\{0,1,2,\ldots,25\}.$ The number of members $s$ of $S$ such that $f(s)$ has remainder zero when divided by $6$ is:
  1. $25$
  2. $22$
  3. $21$
  4. $18$
  5. $17$

Question 17

Given the distinct points $P(x_1,y_1),$ $Q(x_2,y_2)$ and $R(x_1+x_2,y_1+y_2).$ Line segments are drawn connecting these points to each other and to the origin $O.$ Of the three possibilities: $(1)$ parallelogram, $(2)$ straight line, $(3)$ trapezoid, figure $OPRQ,$ depending upon the location of the points $P,$ $Q,$ and $R,$ can be:
  1. $(1)$ only
  2. $(2)$ only
  3. $(3)$ only
  4. $(1)$ or $(2)$ only
  5. all three

Question 18

Let $n$ be the number of pairs of values of $b$ and $c$ such that $3x+by+c=0$ and $cx-2y+12=0$ have the same graph. Then $n$ is:
  1. $0$
  2. $1$
  3. $2$
  4. finite but more than $2$
  5. greater than any finite number

Question 19

If $2x-3y-z=0$ and $x+3y-14z=0,$ $z\ne0,$ the numerical value of $\dfrac{x^2+3xy}{y^2+z^2}$ is:
  1. $7$
  2. $2$
  3. $0$
  4. $-\dfrac{20}{17}$
  5. $-2$

Question 20

The sum of the numerical coefficients of all the terms in the expansion of $(x-2y)^{18}$ is:
  1. $0$
  2. $1$
  3. $19$
  4. $-1$
  5. $-19$