Question

y is inversely proportional to x for positive values. When x = 3.5, y = 4.2 Work out the value of y when x = 5.6​

Answer 1

• x1y1=x2y2
• 3.5(4.2)=(5.6)Y2
• 14.7=5.6y2[/tex]
• y2=2.6

y has value 2.6

Answer 2

y = 2.625

Explanation:

If y is inversely proportional to x for positive value:

`y \propto (1)/(x)\implies y=(k)/(x)\quad \textsf{for some constant }k, k > 0`

`\begin{aligned}\textsf{when }x=3.5, y=4.2 \implies 4.2 & =(k)/(3.5)\\k & = 4.2 \cdot 3.5\\k & = 14.7\end{aligned}`

`\textsf{Therefore }y=(14.7)/(x)`

`\begin{aligned}\textsf{when }x=5.6\implies y & =(14.7)/(5.6)\\y & = 2.625\end{aligned}`