Examples
Last updated at August 5, 2026 by Teachoo
Transcript
Question 3 Find the equation of all lines having slope 2 and being tangent Equation of curve is y + 2/(š„ ā 3) = 0 Differentiating both sides w.r.t x (šš¦ )/šš„ + (š )/šš„ (2/(š„ ā 3))=0 (šš¦ )/šš„ =ā(š )/šš„ (2/(š„ ā 3)) (šš¦ )/šš„ =ā2 (š )/šš„ (š„ā3)^(ā1) (šš¦ )/šš„ =ā2ć Ć ā(š„ā3)ć^(ā1ā1) (šš¦ )/šš„ =2(š„ā3)^(ā2) (š š )/š š =š/(š ā š)^š Given that slope = 2 šš¦/šš„ = 2 2/(š„ ā 3)^2 = 2 1/(š„ ā 3)^2 = 1 (š„ā3)^2 = 1 š„ā3 = ±1 x ā 3 = 1 x = 4 x ā 3 = ā 1 x = 2 x ā 3 = ā 1 x = 2 So, x = 4 & x = 2 Finding value of y If x = 2 y = (ā2)/(š„ ā 3) y = (ā2)/(2 ā 3) š¦=2 Thus, point is (2, 2) If x = 4 y = (ā2)/(š„ ā 3) y = (ā2)/(4 ā 3) š¦=ā2 Thus, point is (4, ā2) Thus, there are 2 tangents to the curve with slope 2 and passing through points (2, 2) and (4, ā 2) We know that Equation of line at (š„1 , š¦1)& having Slope m is š¦āš¦1=š(š„āš„1) Equation of tangent through (2, 2) is š¦ ā 2 = 2 (š„ ā2) š¦ ā 2 = 2š„ ā 4 šāšš+š = š Equation of tangent through (4, ā2) is š¦ ā(ā2) = 2 (š„ ā4) š¦ + 2 = 2š„ ā 8 š ā šš + šš = š to the curve y + 2/(š„ ā 3) = 0