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y is inversely proportional to the square of x.
A table of values for x and y is shown.

a) Express y in terms of x.
b) Work out the positive value of x when y = 25

y is inversely proportional to the square of x A table of values for x and y is shown a Express y in terms of x b Work out the positive value of x when y 25 class=

Respuesta :

Answer:

a) [tex]y=\frac{K}{x^{2} }[/tex]

b) [tex]x=\frac{2}{5}[/tex]

Step-by-step explanation:

If [tex]y[/tex] is inversely propotional to the square of [tex]x[/tex], then the relation would be like

[tex]y=\frac{K}{x^{2} }[/tex]

Where [tex]K[/tex] is the constant of propotionality.

Now, we need to use a pair from the table to find the constant of proportionality, we are gonna use [tex](1,4)[/tex]

[tex]y=\frac{K}{x^{2} }\\4=\frac{K}{(1)^{2} } \\K=4[/tex]

Replacing this constant, the expression between variables is

[tex]y=\frac{4}{x^{2} }[/tex]

Which is the answer to a).

Now, if [tex]y=25[/tex] the value of [tex]x[/tex] would be

[tex]y=\frac{4}{x^{2} }\\25=\frac{4}{x^{2} }\\x^{2} =\frac{4}{25}\\ x=\sqrt{\frac{4}{25} }\\ x=\frac{2}{5}[/tex]

Therefore, the answer to b) is [tex]x=\frac{2}{5}[/tex]

To find the value of [tex]x[/tex] and [tex]y[/tex] we have to find the proportionality constant. The y in terms of x is [tex]y=\frac{2}{\sqrt{x}}[/tex] and positive value of [tex]x=\frac{2}{5}[/tex].

Given:

From the given problem y is inversely proportional to the square of x.  

A table of values for x and y is shown.

From the table:

(a) As we know that, y is inversely proportional to the square of x,

Here k is proportionality constant.

[tex]y\propto\frac{1}{\sqrt{x}}[/tex]

Then, [tex]1\times \sqrt4 =2\times \sqrt{1}=2=k[/tex]

Therefore, y in terms of x is [tex]y=\frac{2}{\sqrt{x}}[/tex].

(b) we have an expression of [tex]y=\frac{2}{\sqrt{x}}[/tex]

Putting the value of [tex]y=25[/tex], we get:

[tex]25=\frac{4}{{x^2}}\\x^2=\frac{4}{25}\\\\x=\sqrt{\frac{4}{25}}\\x=\frac{2}{5}[/tex]

Therefore, the positive value of [tex]x=\frac{2}{5}[/tex].

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