Find the equations of tangents to the curve y=x^3+2x+6 which is perpendicular to the line x+14y+4=0
Dear Student,
y = x3 + 2x + 6
Slope of tangent = m1 = = 3x2 + 2
Slope of perpendicular line = m2 =
m1 . m2 = -1
m1 = 14
3x2 + 2 = 14
x = 2
Therefore the curve has tangents at x = 2 and x = -2
and these points also lie on the given curve
Equation of tangent - y = 14x + c
Coordinates of points of tangency
At x = 2 , y = 23 + 2(2) + 6 = 18
At x = -2 , y = (-2)3 + 2(-2) + 6 = -6
18 = 14(2) + c
c = -10
-6 = 14(-2) + c
c = 22
Equation of tangent - y = 14x - 10 and y = 14x + 22
Regards
y = x3 + 2x + 6
Slope of tangent = m1 = = 3x2 + 2
Slope of perpendicular line = m2 =
m1 . m2 = -1
m1 = 14
3x2 + 2 = 14
x = 2
Therefore the curve has tangents at x = 2 and x = -2
and these points also lie on the given curve
Equation of tangent - y = 14x + c
Coordinates of points of tangency
At x = 2 , y = 23 + 2(2) + 6 = 18
At x = -2 , y = (-2)3 + 2(-2) + 6 = -6
18 = 14(2) + c
c = -10
-6 = 14(-2) + c
c = 22
Equation of tangent - y = 14x - 10 and y = 14x + 22
Regards