10. The asymptote parallel to the [tex]y[/tex]-axis of the curve [tex]\left(x^2 + y^2\right) x - a y^2 = 0[/tex] is:

(a) [tex]y = -a[/tex]
(b) [tex]x = -a[/tex]
(c) [tex]y = a[/tex]
(d) [tex]x = a[/tex]



Answer :

To find the asymptote parallel to the y-axis for the curve given by the equation

[tex]\[ (x^2 + y^2) x - a y^2 = 0, \][/tex]

we can start by rearranging the equation to make it easier to analyze:

[tex]\[ x^3 + x y^2 - a y^2 = 0. \][/tex]

Here, we want to find the values of \( x \) such that, as \( y \) tends to infinity, the equation describes an asymptote parallel to the y-axis. Essentially, we seek vertical asymptotes where \( x \) tends to some constant value while \( y \) goes to infinity.

To identify such points, we need to analyze how \( x \) behaves as \( y \) grows very large. Suppose \( y \) is very large, we would expect that terms including \( y^2 \) are dominant. Let's re-examine the equation under this assumption:

[tex]\[ x^3 + (x - a)y^2 = 0. \][/tex]

Dividing through by \( y^2 \):

[tex]\[ \frac{x^3}{y^2} + (x - a) = 0. \][/tex]

Since \( y \) is very large, the term \(\frac{x^3}{y^2}\) becomes very small and in the limit can be considered approaching zero. Thus, the dominant terms reduce to:

[tex]\[ x - a \approx 0, \][/tex]

which implies:

[tex]\[ x \approx a. \][/tex]

Thus, we determined that as \( y \) approaches infinity, \( x \) approaches the constant \( a \), suggesting that \( x = a \) is a vertical asymptote.

Hence, the correct option is:

(d) [tex]\( x = a \)[/tex].