WBJEE 2022 Math Solved Paper

(A, B, C are correct )
Hint: (A) y2=20x=4(5)x‌‌∴ Tangent :y=mx+‌

a

m

for m=1,a=5
∴y=x+5 is a tangent to y2=20x
(B) 9x2+16y2=144 c2=a2m2+b2 y=x+5⇒m=1;c=5 ⇒‌

x2

16

+‌

y2

9

=1 ∴52=16(1)2+9⇒ True
∴y=x+5 is a tangent to 9x2+16y2=144
(C) c2=a2m2−b2
‌

x2

29

−‌

y2

4

=1→a2=29;b2=4
52=29(1)2−4→ True ∴y=x+5 is a tangent
(D)∴y=x+5 is NOT tangent to x2+y2=25
(A), (B), (C) are correct.