NARAYANA IIT/PMT ACADEMY - Narayanaicc.com
NARAYANA IIT/PMT ACADEMY - Narayanaicc.com
NARAYANA IIT/PMT ACADEMY - Narayanaicc.com
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Ans<br />
Sol<br />
(C) f ' x f x ,0 x<br />
(C)<br />
For<br />
f ' x<br />
<strong>NARAYANA</strong> <strong>IIT</strong>/<strong>PMT</strong> <strong>ACADEMY</strong><br />
JEE ADVANCE : 2013<br />
1<br />
4<br />
1<br />
x 0, g ' x 0<br />
4<br />
x<br />
x<br />
e f ' x e f x 0<br />
f x for<br />
(PAPER – II) CODE: 0<br />
3<br />
(D) f ' x f x , x 1<br />
4<br />
1<br />
x 0, 4<br />
Paragraph for Question 51 and 52<br />
Let PQ be a focal chord of the parallel<br />
lying on the line y 2 x a, a 0.<br />
y<br />
2<br />
4 ax . The tangents of the parabola at P and Q meet at a point<br />
51 Length of chord PQ is<br />
(A) 7a (B) 5a (C) 2a (D) 3a<br />
Ans (B)<br />
Sol<br />
, 2at)<br />
P (at2 y=2x+a<br />
(0, 0)<br />
(-a, -a)<br />
S<br />
Q<br />
a 2a<br />
Q , t<br />
2 t<br />
2<br />
1<br />
PQ a t<br />
………(i)<br />
t<br />
Eq of tangent at P<br />
2<br />
ty x at<br />
As it passes through (–a, –a)<br />
– at = – a + at 2<br />
t 2 + t – 1 = 0<br />
5 1<br />
t (for p, t > 0)<br />
2<br />
2<br />
5 1 2 5 1<br />
PQ a<br />
2 5 1 5 1<br />
<strong>NARAYANA</strong> GROUP OF EDUCATIONAL INSTITUTIONS - INDIA<br />
31
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