If y= mx+4 is a tangent to both the parabola y^2=4xand x^2=2 by. Then the value of b is :

Question

Accepted Answer

Correct answer: C. (c) JEE Main 2020 y= mx=4 … (i) y^2=4xtangent y= mx+ am ⇒y= mx+ 1m … (ii) From (i) and (ii) 4= 1m ⇒m= 14 So line y= 14x+4 is also tangent to parabola x^2=2 by, so solve x^2=2b ( x+164 ) ⇒2x^2- bx-16b=0 ⇒D=0 ⇒b^2+32 4b=0 b=-128 ,b=0 (not possible)

$If y = mx + 4 is a tangent to both the parabola y^{2} = 4 x and x^{2} = 2 by . Then the value of b is :$

Solution

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