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Ex 4A
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Solutions
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The order of a matrix is given by: Row × Column
(a)
$$ 3 \times 2 $$
(b)
$$ 1 \times 3 $$
(c)
$$ 3 \times 3 $$
(d)
$$ 2 \times 1$$
(e)
$$ 1 \times 1$$
(f)
$$ 2 \times 2$$
(a)
$$ \text{Equal} $$
(b)
$$ \text{Not equal, since the elements are different} $$
(c)
$$ \text{Not equal, since the order of the matrices are different} $$
(d)
$$ \text{Not equal, since the order of the matrices are different} $$
(i)
\begin{align*} \textbf{F} & = \left( \begin{matrix} 4 & 0 & 5 & 6 \\ 8 & 7 & 5 & 3 \end{matrix} \right) \end{align*}
(ii)
$$ \text{Banana} $$
(iii)
\begin{align*} \text{Sum of elements in first row} & = 4 + 0 + 5 + 6 \\ & = 15 \\ \\ \text{The boys in the class consume } & 15 \text{ fruits in total} \end{align*}
(iv) Find the sum of the elements in the last column of F
\begin{align*} \text{No. of students who like durian best} & = 6 + 3 \\ & = 9 \end{align*}
(a)
$$ \text{Not equal, since the order of the matrices are different} $$
(b)
$$ \text{Equal} $$
\begin{align} \textbf{B} & = \textbf{Q} \\ \\ \textbf{C} & = \textbf{O} \\ \\ \textbf{D} & = \textbf{I} \\ \\ \textbf{E} & = \textbf{H} \\ \\ \textbf{F} & = \textbf{P} \\ \\ \textbf{G} & = \textbf{L} \\ \\ \textbf{J} & = \textbf{N} \end{align}
(a)
\begin{align*} 2a & = 2 \\ a & = {2 \over 2} \\ a & = 1 \\ \\ b & = 3 \\ \\ c & = 5 \\ \\ k & = 7 \end{align*}
(b)
\begin{align*} a & = 3 \\ \\ b & = 13 \\ \\ d & = 7 \\ \\ c & = 6 \end{align*}
(c)
\begin{align*} 2x & = 14 \\ x & = {14 \over 2} \\ x & = 7 \\ \\ 2k & = 18 \\ k & = {18 \over 2} \\ k & = 9 \\ \\ 3y & = 15 \\ y & = {15 \over 3} \\ y & = 5 \\ \\ 6h & = 36 \\ h & = {36 \over 6} \\ h & = 6 \end{align*}
(d)
\begin{align*} 2x - 3 & = 7 \\ 2x & = 7 + 3 \\ 2x & = 10 \\ x & = {10 \over 2} \\ x & = 5 \\ \\ y + 4 & = 6 \\ y & = 6 - 4 \\ y & = 2 \end{align*}
(e)
\begin{align*} {1 \over 2}x & = 3 \\ x & = {3 \over {1 \over 2}} \\ x & = 6 \\ \\ h & = x + 4 \\ h & = 6 + 4 \\ h & = 10 \\ \\ k - 9 & = 5 \\ k & = 5 + 9 \\ k & = 14 \\ \\ 3y & = 27 \\ y & = {27 \over 3} \\ y & = 9 \end{align*}
(f)
\begin{align*} 2x - 5 & = 5 \\ 2x & = 5 \\ x & = {5 \over 2} \\ \\ y - 4 & = 0 \\ y & = 4 \\ \\ z + 3 & = 0 \\ z & = -3 \\ \\ 5k & = 0 \\ k & = {0 \over 5} \\ k & = 0 \end{align*}
(i)
\begin{align*} \textbf{S} & = \left( \begin{matrix} 0 & 3 & 1 & 7 \\ 3 & 0 & 4 & 2 \\ 1 & 4 & 0 & 5 \\ 7 & 2 & 5 & 0 \end{matrix} \right) \end{align*}
(ii)
$$ \text{5 goals} $$
(iii)
$$ \text{An impossible outcome in which a particular team plays against itself} $$
(iv)
\begin{align*} \text{Sum of elements in second row} & = 3 + 0 + 4 + 2 \\ & = 9 \\ \\ \text{Team } B \text{ scored } & 9 \text{ goals in total} \end{align*}
(v)
$$ \text{About the diagonal of zeros, the elements represents the goals scored in the same match} $$