The rate of change of m(t), with respect to t, at t = l is (A) −2 (B) 2

Question

Let a(t) is a function of t such that da/dt = 2 for all the values of t and a = 0 when t = 0. Further y = m(t) x + c(t) is the tangent to the curve y = x² − 2ax + a² + a at the point whose abscissa is 0. Then

The rate of change of m(t), with respect to t, at t = l is 

(A) −2 

(B) 2 

(C) − 4 

(D) 4

Answer 1

Answer is (C) − 4

m(t) = - 4t

Therefore,

dm/dt = - 4

⇒ dm/dt|_{at t=l} = - 4