Q. The length intercepted by the curve $y^{2} = 4x$ on the line satisfying $dy/dx = 1$ and passing through point (0, 1), is given by

A) 1
B) 2
C) 0
D) None of these
Explanation

(c)
Given curve is $y^{2} = 4x$ …(i)
Let the equation of line be $y = mx + c$
Since, $\frac{dy}{dx} = m = 1$ and above line is passing through the point (0, 1)
$1 = 1(0) + c\ \Rightarrow \ c = 1$
$y = x + 1$ …(ii)
On solving Eqs. (i) and (ii), we get
$x = 1$ and $y = 2$
This shows that line touch the curve at one point. So, length of intercept is zero.

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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