Given [tex]$2p = \frac{2}{3}(q - 5r)$[/tex], express [tex]$r$[/tex] in terms of [tex][tex]$p$[/tex][/tex] and [tex]$q$[/tex]. Hence, find the value of [tex]$r$[/tex] when [tex][tex]$p = 4$[/tex][/tex] and [tex]$q = 27$[/tex].

Jawapan / Answer:
[4 markah / 4 marks]



Answer :

To solve the given equation [tex]\( 2p = \frac{2}{3}(q - 5r) \)[/tex] for [tex]\( r \)[/tex] in terms of [tex]\( p \)[/tex] and [tex]\( q \)[/tex], follow these steps:

1. Start with the given equation:
[tex]\[ 2p = \frac{2}{3}(q - 5r) \][/tex]

2. Eliminate the fraction by multiplying both sides by 3:
[tex]\[ 3 \cdot 2p = 2(q - 5r) \][/tex]
This simplifies to:
[tex]\[ 6p = 2(q - 5r) \][/tex]

3. Divide both sides by 2 to isolate the terms involving [tex]\( r \)[/tex]:
[tex]\[ 3p = q - 5r \][/tex]

4. Rearrange the equation to solve for [tex]\( r \)[/tex]:
[tex]\[ q - 5r = 3p \][/tex]
Isolate [tex]\( r \)[/tex] by moving terms involving [tex]\( q \)[/tex] and [tex]\( p \)[/tex]:
[tex]\[ q - 3p = 5r \][/tex]
Divide both sides by 5:
[tex]\[ r = \frac{q - 3p}{5} \][/tex]
Thus, [tex]\( r \)[/tex] in terms of [tex]\( p \)[/tex] and [tex]\( q \)[/tex] is:
[tex]\[ r = \frac{q - 3p}{5} \][/tex]

5. Substitute [tex]\( p = 4 \)[/tex] and [tex]\( q = 27 \)[/tex] into the equation to find the value of [tex]\( r \)[/tex]:
[tex]\[ r = \frac{27 - 3 \cdot 4}{5} \][/tex]
Calculate the expression inside the parentheses:
[tex]\[ 27 - 3 \cdot 4 = 27 - 12 = 15 \][/tex]
Now divide by 5:
[tex]\[ r = \frac{15}{5} = 3 \][/tex]

So the value of [tex]\( r \)[/tex] when [tex]\( p = 4 \)[/tex] and [tex]\( q = 27 \)[/tex] is:
[tex]\[ r = 3 \][/tex]

Thus, the final expressions are:
[tex]\[ r = -0.6p + 0.2q \][/tex]
and when [tex]\( p = 4 \)[/tex] and [tex]\( q = 27 \)[/tex], [tex]\( r = 3 \)[/tex].