2021 H2 Math Paper 1 Answers

1
a=4,b=6,c=0,d=7.{a=4, b=-6, c=0, d=7.}
2
(a)
(b)
x=1+5 or x=1+7.{x=1 + \sqrt{5} \textrm{ or } x=- 1 + \sqrt{7}.}
3
y=12x+72.{y = \frac{1}{2} x + \frac{7}{2}.}
4
(a)
z=1,  argz=14π.{|z|=1, \; \arg z = \frac{1}{4} \pi.}
z2=i.{z^2 = \mathrm{i}.}
(b)
0.{0.}
5
(a)
1x+2+3x+3+2x+4{\displaystyle \frac{- 1}{x+2} + \frac{3}{x+3} + \frac{- 2}{x+4}}
(b)
16+1n+32n+4.{\displaystyle \frac{1}{6} + \frac{1}{n+3} - \frac{2}{n+4}.}
(c)
16.{\displaystyle \frac{1}{6}.}
6
(a)
x=0,  x=4a.{x=0, \; x=4a.}
(b)
y=12a.{y=\frac{1}{2a}.}
(c)
Translation of 2a{2a} units in the negative x{x}-direction.
7
esin1x=1+x+12x2+13x3+{\mathrm{e}^{\sin^{-1}x} = 1 + x + \frac{1}{2} x^2 + \frac{1}{3} x^3 + \ldots}
8
(a)
x+2z=3{- x + 2 z = - 3}
(c)
(i)
λ=1,  μ=1.{\lambda = -1, \; \mu = 1.}
(151),  (331).{\begin{pmatrix} 1 \\ 5 \\ - 1 \end{pmatrix}, \; \begin{pmatrix} - 3 \\ 3 \\ 1 \end{pmatrix}.}
(ii)
26.{2 \sqrt{6}.}
9
(a)
Maximum point (14π,  122e14π){\displaystyle \left( \frac{1}{4} \pi, \; \frac{1}{2} \sqrt{2} \mathrm{e}^{\frac{1}{4} \pi} \right)}
(c)
π8(eπ3).{\displaystyle \frac{\pi}{8} \left(\mathrm{e}^\pi - 3 \right).}
10
(a)
dNdt=kN.{\displaystyle \frac{\mathrm{d}N}{\mathrm{d}t} = kN.}

N=Aekt.{N = A \mathrm{e}^{kt}.}

k=12ln3.{k = \frac{1}{2} \ln 3.}

2ln10ln3 min.{\displaystyle \frac{2 \ln 10}{\ln 3} \textrm{ min.}}
(b)
dNdt=kNd.{\displaystyle \frac{\mathrm{d}N}{\mathrm{d}t} = kN - d.}

t=2ln3ln(Nln32d100ln32d).{\displaystyle t = \frac{2}{\ln 3} \ln \left( \frac{N \ln 3 - 2d}{100 \ln 3 - 2d} \right).}

N=2ln3(d+(50ln3d)etln32).{\displaystyle N = \frac{2}{\ln 3} \Big( d + (50 \ln 3 - d) \mathrm{e}^{\frac{t\ln 3}{2}} \Big).}
(c)
(i)
d>50ln3{d > 50 \ln 3}
(ii)
5.35 min.{5.35 \textrm{ min.}}
11
(a)
2α(πβ+sinβ).{2\alpha(\pi - \beta + \sin \beta).}
(c)
β=1.90.{\beta = 1.90.}
(d)
Greatest height =22.9 m.{\textrm{Greatest height } = 22.9 \textrm{ m.}}
Least height =15.1 m.{\textrm{Least height } = 15.1 \textrm{ m.}}

Solutions

Full solutions (with working)
The actual questions are the copyright of UCLES and MOE. These answers are my own and any errors therein are mine alone.
Desmos was used to generate the sketch of the curves in Q2 and Q6.