Questions

Solve the Following Question.(3 Marks)

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12 questions · self-marked practice — reveal the answer and mark yourself.

Question 43 Marks
Solve the following inequations graphically in a two-dimensional plane: $\left(\frac{1}{4}\right) x+\left(\frac{1}{2}\right) y \leq 1$
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Question 123 Marks
Find all pairs of consecutive even positive integers, both of which are larger than 5 such that their sum is less than 23.
Answer
Let $2 n, 2 n+2$ be two positive consecutive integers where $n \geq 1 \in Z$.
Given that $2 n>5$ and $2 n+2>5$
$
\begin{aligned}
& \therefore n>\frac{5}{2} \text { and } 2 n>3 \\
& \therefore n>\frac{5}{2} \text { and } n>\frac{3}{2} \\
& \therefore n>\frac{5}{2} \ldots . . . \text { (i) }
\end{aligned}
$
Also $(2 n)+(2 n+2)<23$
$
\begin{aligned}
& \therefore 4 \mathrm{n}+2<23 \\
& \therefore 4 \mathrm{n}<21 \\
& \therefore \mathrm{n}<\frac{21}{4} \ldots . . . \text { (ii) }
\end{aligned}
$
From (i) and (ii)
$
\begin{aligned}
& \frac{5}{2}<n<\frac{21}{4} \text { and } n \text { is an integer. } \\
& \therefore n=3,4,5 \\
& n=3 \text { gives } 2 n=6,2 n+2=8 \\
& n=4 \text { gives } 2 n=8,2 n+2=10 \\
& n=5 \text { gives } 2 n=10,2 n+2=12
\end{aligned}
$
$\therefore$ The pairs of positive even consecutive integers are $(6,8)(8,10),(10,12)$
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