Qus : 1
2 If the foci of the ellipse x 2 25 + y 2 b 2 = 1 and the hyperbola x 2 144 − y 2 81 = 1 25 are coincide, then the value of b 2
1 25 2 16 3 64 4 49 Go to Discussion
Solution Qus : 2
3 At how many points the following curves intersect y 2 9 − x 2 16 = 1 and x 2 4 + ( y − 4 ) 2 16 = 1
1 0 2 1 3 2 4 4 Go to Discussion
Solution Qus : 3
3 If ( x a ) 2 + ( y b ) 2 = 1 , ( a > b ) and x 2 − y 2 = c 2 cut at right angles, then
1 a 2 + b 2 = 2 c 2 2 b 2 − a 2 = 2 c 2 3 a 2 − b 2 = 2 c 2 4 a 2 − b 2 = c 2 Go to Discussion
Solution If
x 2 a 2 + y 2 b 2 = 1 and
x 2 c 2 + y 2 d 2 = 1 are orthogonal.
Then
a 2 − b 2 = c 2 − d 2
Similarly
If x 2 a 2 + y 2 b 2 = 1 and x 2 − y 2 = c 2 are orthogonal.
It means
x 2 a 2 + y 2 b 2 = 1 and x 2 c 2 + y 2 − c 2 = 1 are orthogonal
Then
a 2 − b 2 = c 2 − ( − c 2 )
a 2 − b 2 = 2 c 2
Qus : 4
1 If the line a 2 x + a y + 1 = 0 , for some real number a , is normal to the curve x y = 1
then
1 a < 0 2 0 < a < 1 3 a > 0 4 − 1 < a < 1 Go to Discussion
Solution
Problem:
The line a 2 x + a y + 1 = 0 is normal to the curve x y = 1 . Find possible values of a ∈ R .
Step 1: Slope of Line
Rewrite: y = − a x − 1 a → slope = − a
Step 2: Curve Derivative
x y = 1 ⇒ d y d x = − y x
Slope of normal = x y
Match Slopes
− a = x y ⇒ x = − a y
Plug into Curve
x y = 1 ⇒ ( − a y ) ( y ) = 1 ⇒ y 2 = − 1 a
For real y , we need a < 0
✅ Final Answer:
a < 0
Qus : 5
2 Equation of the common tangents with a positive slope to the circle
and
is
1 2 3 4 Go to Discussion
Solution Qus : 7
3 The locus of the intersection of the two lines √ 3 x − y = 4 k √ 3 and k ( √ 3 x + y ) = 4 √ 3 , for different
values of k, is a hyperbola. The eccentricity of the hyperbola is:
1 1.5 2 √ 3 3 2 4 √ 3 2 Go to Discussion
Solution Qus : 8
3 If the foci of the ellipse b 2 x 2 + 16 y 2 = 16 b 2 and the hyperbola 81 x 2 − 144 y 2 = 81 × 144 25 coincide, then the value of b , is
1 1 2 √ 5 3 √ 7 4 3 Go to Discussion
Solution Qus : 9
1 If 3 x + 4 y + k = 0 is a tangent to the hyperbola ,9 x 2 − 16 y 2 = 144 then the value of K is
1 0 2 1 3 -1 4 -3 Go to Discussion
Solution Qus : 10
2 If PQ is a double ordinate of the hyperbola x 2 a 2 − y 2 b 2 = 1 such that OPQ is an equilateral triangle,
where O is the centre of the hyperbola, then which of the following is true?
1 b 2 > − a 2 √ 3 2 b 2 > a 2 3 3 b 2 < a 2 3 4 b 2 < − a 2 3 Go to Discussion
Solution Qus : 11
2
Find foci of the equation x^2 + 2x – 4y^2 + 8y – 7 = 0
1 (\sqrt[]{5}\pm1,1) 2 (-1\pm\sqrt[]{5},1) 3 (-1,\sqrt[]{5}\pm1) 4 (1,-1\pm\sqrt[]{5}) Go to Discussion
Solution
Finding Foci of a Conic
Given Equation: x^2 + 2x - 4y^2 + 8y - 7 = 0
Step 1: Complete the square
⇒ (x + 1)^2 - 4(y - 1)^2 = 4
Rewriting: \frac{(x + 1)^2}{4} - \frac{(y - 1)^2}{1} = 1
This is a horizontal hyperbola with:
Center: (-1, 1)
a^2 = 4 , b^2 = 1
c = \sqrt{a^2 + b^2} = \sqrt{5}
✅ Foci:
(-1 \pm \sqrt{5},\ 1)
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