The Student Room Group

Core 2 math help?

Please help me start! :frown:

Y = x^-3 + 48x
Find the equation of the two tangents parallel to the x-axis
Reply 1
Original post by Bhansongal98
Please help me start! :frown:

Y = x^-3 + 48x
Find the equation of the two tangents parallel to the x-axis


Differentiate, set the derivative equal to zero and solve the quadratic. That'll give you two points at which the gradient is 0 and hence the tangent parallel to the x-axis. Then you form your equation by doing y - y_1 = m(x-x_1) where you find y_1 by plugging x_1 into your equation of the curve.

Quick Reply

Latest