Example 16 - Find equation of all lines having slope 2, tangent

Example 16 - Chapter 6 Class 12 Application of Derivatives - Part 2
Example 16 - Chapter 6 Class 12 Application of Derivatives - Part 3 Example 16 - Chapter 6 Class 12 Application of Derivatives - Part 4

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Question 3 Find the equation of all lines having slope 2 and being tangent Equation of curve is y + 2/(š‘„ āˆ’ 3) = 0 Differentiating both sides w.r.t x (š‘‘š‘¦ )/š‘‘š‘„ + (š‘‘ )/š‘‘š‘„ (2/(š‘„ āˆ’ 3))=0 (š‘‘š‘¦ )/š‘‘š‘„ =āˆ’(š‘‘ )/š‘‘š‘„ (2/(š‘„ āˆ’ 3)) (š‘‘š‘¦ )/š‘‘š‘„ =āˆ’2 (š‘‘ )/š‘‘š‘„ (š‘„āˆ’3)^(āˆ’1) (š‘‘š‘¦ )/š‘‘š‘„ =āˆ’2怖 Ɨ āˆ’(š‘„āˆ’3)怗^(āˆ’1āˆ’1) (š‘‘š‘¦ )/š‘‘š‘„ =2(š‘„āˆ’3)^(āˆ’2) (š’…š’š )/š’…š’™ =šŸ/(š’™ āˆ’ šŸ‘)^šŸ Given that slope = 2 š‘‘š‘¦/š‘‘š‘„ = 2 2/(š‘„ āˆ’ 3)^2 = 2 1/(š‘„ āˆ’ 3)^2 = 1 (š‘„āˆ’3)^2 = 1 š‘„āˆ’3 = ±1 x āˆ’ 3 = 1 x = 4 x āˆ’ 3 = āˆ’ 1 x = 2 x āˆ’ 3 = āˆ’ 1 x = 2 So, x = 4 & x = 2 Finding value of y If x = 2 y = (āˆ’2)/(š‘„ āˆ’ 3) y = (āˆ’2)/(2 āˆ’ 3) š‘¦=2 Thus, point is (2, 2) If x = 4 y = (āˆ’2)/(š‘„ āˆ’ 3) y = (āˆ’2)/(4 āˆ’ 3) š‘¦=āˆ’2 Thus, point is (4, –2) Thus, there are 2 tangents to the curve with slope 2 and passing through points (2, 2) and (4, āˆ’ 2) We know that Equation of line at (š‘„1 , š‘¦1)& having Slope m is š‘¦āˆ’š‘¦1=š‘š(š‘„āˆ’š‘„1) Equation of tangent through (2, 2) is š‘¦ āˆ’ 2 = 2 (š‘„ āˆ’2) š‘¦ āˆ’ 2 = 2š‘„ āˆ’ 4 š’šāˆ’šŸš’™+šŸ = šŸŽ Equation of tangent through (4, āˆ’2) is š‘¦ āˆ’(āˆ’2) = 2 (š‘„ āˆ’4) š‘¦ + 2 = 2š‘„ āˆ’ 8 š’š āˆ’ šŸš’™ + šŸšŸŽ = šŸŽ to the curve y + 2/(š‘„ āˆ’ 3) = 0

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