Question

The equation $\frac{x^2}{10-a}+\frac{y^2}{4-a}=1$ represents an ellipse if

• A. $a<4$
• B. $a>4$
• C. $4<a<10$
• D. $a>10$

Answer 1

The correct option is A $a<4$

Given the equation $\frac{x^2}{10-a}+\frac{y^2}{4-a}=1$ represents an

ellipse if $10-a>0$ .....(1) and

$4-a>0$ .....(2).

From (1) we get, $a<10$ .....(3) and

from (2) we get, $a<4$ ......(4).

Combining (3) and (4) we get, $a<4$.