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ITMC 2018 Grade 11 National Preliminary set01

Question 1

Printed positive marks are preserved per question. The source uses different blank-answer and incorrect-answer rules by section, including an optional bonus penalty; the import does not reproduce that complete official scoring scheme.

Which function is a decreasing exponential function? The source prints the label D twice; the fifth option is identified as E here.
  1. $f_1(x)=(1/x)^{13}$, $x\ne0$
  2. $f_2(x)=0^x$, $x\ne0$
  3. $f_3(x)=1^{2x}$, $x\in\mathbb R$
  4. $f_4(x)=(\sqrt3-\sqrt2)^{-x}$, $x\in\mathbb R$
  5. $f_5(x)=(\log_2 3)^{-x}$, $x\in\mathbb R$

Question 2

Given $\log_{72}2=a$, find $\log_{72}3$.
  1. $\frac2{1+3a}$
  2. $\frac{1+3a}2$
  3. $\frac{1-3a}2$
  4. $\frac{3a-1}2$
  5. $\frac1{3a}-2$

Question 3

Let $f(x)=\log_{2561}x$. Which set is the domain of $f\circ f$?
  1. $[1,\infty)$
  2. $(1,\infty)$
  3. $(0,\infty)$
  4. $[0,\infty)$
  5. $(0,1)\cup(1,\infty)$

Question 4

$ABCD$ is a rectangle. Construct square $ABEF$ with $C$ on $BE$ and $D$ on $AF$, and square $AGHD$ with $G$ on $AB$ and $H$ on $CD$. Their areas are $\log_4 27$ and $\log_9 8$, respectively. Find the area of $ABCD$.
  1. $\frac32\log_2 3$
  2. $\frac94\log_3 2$
  3. $\frac32$
  4. $\frac94$
  5. None of these

Question 5

Which of these values is the largest negative real number? Angles are in radians.
  1. $\cos2$
  2. $\cos3$
  3. $\cos4$
  4. $\cos5$
  5. $\cos6$

Question 6

For real $x$, simplify $\sin(x-1)\cos1+\cos(x-1)\sin1$.
  1. $\sin x$
  2. $\cos x$
  3. $1$
  4. $\sin x\cos2$
  5. $\cos x\cos2$

Question 7

In triangle $ABC$, $\cos A=5/13$ and $\cos B=3/5$. Find $\cos C$.
  1. $-\frac{63}{65}$
  2. $-\frac{33}{65}$
  3. $1$
  4. $\frac{33}{65}$
  5. $\frac{63}{65}$

Question 8

Let $\theta$ be acute and $\csc\theta+\cot\theta=3+2\sqrt2$. Find $\cos^2\theta$.
  1. $\frac18$
  2. $\frac78$
  3. $\frac{17}{72}$
  4. $\frac19$
  5. $\frac89$

Question 9

Find $\sqrt3\,\sqrt[3]2$.
  1. $\sqrt2\,\sqrt[3]3$
  2. $\sqrt[6]{108}$
  3. $\sqrt[5]6$
  4. $\sqrt[6]6$
  5. None of these

Question 10

Given $37^x=\sqrt[3]{20}+\sqrt[3]{17}$ and $37^y=\sqrt[3]{400}-\sqrt[3]{340}+\sqrt[3]{289}$, which relation is correct?
  1. $y=-x+1$
  2. $y=-x+\log37$
  3. $y=1/x$
  4. $y=(\log37)/x$
  5. None of these

Question 11

Real $x,y$ satisfy $(x+1)^2+(y+2)^2=0$. Find $(x-1)^2+(y-2)^2$.
  1. $0$
  2. $5$
  3. $10$
  4. $20$
  5. $25$

Question 12

Let $n$ be the greatest integer solution of $\left|\left||x-2018|+2018\right|-2018\right|=543$. Which listed number divides $n$?
  1. $5$
  2. $7$
  3. $11$
  4. $13$
  5. $17$

Question 13

Let $A$ be the solution set of $\log_{x+1}(x^2-3x+1)=1$. Consider (1) $A$ has two elements; (2) the product of all elements of $A$ is 0; (3) the sum of all elements of $A$ is 4. Which is correct?
  1. Fewer than two statements are correct
  2. Only (1) and (2)
  3. Only (1) and (3)
  4. Only (2) and (3)
  5. All three

Question 14

Use $\log_{10}3=0.4771$ and $\log_{10}5=0.6990$ to choose the correct ordering.
  1. $\frac43\lt \log_3 4\lt \sqrt[3]4$
  2. $\log_3 4\lt \frac43\lt \sqrt[3]4$
  3. $\sqrt[3]4\lt \log_3 4\lt \frac43$
  4. $\log_3 4\lt \sqrt[3]4\lt \frac43$
  5. $\frac43\lt \sqrt[3]4\lt \log_3 4$

Question 15

An integer $x\in[0,90]$ satisfies $\tan x^\circ=(\cos10^\circ+\cos70^\circ)/(\sin10^\circ+\sin70^\circ)$. Find $x$.
  1. $30$
  2. $40$
  3. $50$
  4. $60$
  5. $70$

Question 16

Real $x\in[0,2\pi]$ satisfies $\sin(x-4)=-1$. How many statements are correct? (1) $\sin x\lt 0$; (2) $\cos x\gt 0$; (3) $\sin2x\gt 0$; (4) $\cos2x\lt 0$.
  1. $0$
  2. $1$
  3. $2$
  4. $3$
  5. $4$

Question 17

Using $\pi=3.14$ as instructed, evaluate $\arcsin(\sin(-5))$.
  1. $-5$
  2. $-1.28$
  3. $1.28$
  4. $-1.86$
  5. $1.86$

Question 18

With universal set $\mathbb R$, solve $(3-2\sqrt2)^{x^2-5x-6}=(3+2\sqrt2)^{6+5x-x^2}$.
  1. $\varnothing$
  2. $[-1,6]$
  3. $(-\infty,-1]\cup[6,\infty)$
  4. $\mathbb R\setminus\{-1,6\}$
  5. $\mathbb R$

Question 19

The polynomial $x^4+5x^3+px^2+qx+r$ is divisible by $2+5x+6x^2+x^3$, where $p,q,r$ are real. Find $(p+r)q$.
  1. $-8$
  2. $3$
  3. $4$
  4. $8$
  5. $9$

Question 20

Real $x$ satisfies $(x-1)(x-2)(x-3)-(x-1)(x-2)+x-4=0$. Find the sum of all possible $x$.
  1. $-7$
  2. $1$
  3. $3$
  4. $4$
  5. $7$