The tangent to the parabola y2=4x at the point where it intersects the circle x2+y2=5 in the first quadrant, passes through the point:
(A)(−31,34)
(B)(43,47)✓ Correct
(C)(−41,21)
(D)(41,43)
Answer: (B)
Solution
Find where the parabola y2=4x meets the circle x2+y2=5: substituting, x2+4x−5=0, so (x+5)(x−1)=0 and in the first quadrant x=1, y=2, the point (1,2). The tangent to y2=4x at (1,2) uses yy1=2(x+x1), giving 2y=2(x+1), that is y=x+1. Testing the offered points, (43,47) fits since 47=43+1, so the tangent passes through (43,47).
JEE Main · 2019 · 08 Apr 2019 · Shift 2 · Single correct option