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Find the equation of the common tangent to the curves `y^2=8x` and xy=-1.A. 3y=9y+2B. y=2x+1C. 2y=x+8D. y=x+2 |
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Answer» Correct Answer - D The equation of tangent to `y^(2)=8x` is `y=mx+2/m` If it touches xy=1, then `x(mx+2/m)=-1" must have equal roots"` `rArr" "mx^(2)+2/mx+1=0" must have equal roots"` `rArr" "4/m^(2)-4m=0rArrm^(3)-1=0rArrm=1.` Substituting the value of m in (i), we get y=x+2 as the equation of the common tangent. |
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