The expression for C in terms of y where C is directly proportional to the square root of y is C=3.2√y and the value of C at y=400 is 64.
What is directly proportional relationship?
Let there are two variables p and q
Then, p and q are said to be directly proportional to each other if
[tex]p = kq[/tex]
where k is some constant number called constant of proportionality.
This directly proportional relationship between p and q is written as
[tex]p \propto q[/tex] where that middle sign is the sign of proportionality.
In a directly proportional relationship, increasing one variable will increase another.
C is directly proportional to the square root of y. Thus, the relation can be represented with the proportionality sign as,
[tex]C\propto \sqrt{y}[/tex]
Let k is the proportionality constant. Thus, the equation can be rewritten as,
[tex]C=k \sqrt{y}[/tex]
Here, the value of C is 12.8 and the value of y is 16. Put these values in the above equation as,
[tex]12.8=k \times\sqrt{16}\\12.8=k \times4\\k=\dfrac{12.8}{4}\\k=3.2[/tex]
Thus, the value of constant is 3.2.
- (a) Express C in terms of y.
The value of constant is 3.2. Thus, the expression for C in terms of y is given as,
[tex]C=3.2\sqrt{y}[/tex]
Put the value of y =400 in the above expression.
[tex]C=3.2\sqrt{400}\\C=3.2\times20\\C=64[/tex]
Thus, the expression for C in terms of y where C is directly proportional to the square root of y is C=3.2√y and the value of C at y=400 is 64.
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