L = Length = x
W = Width = 2 x - 4
x = 2 + 3 t
L = x
L = 2 + 3 t
W = 2 x - 4 =
W = 2 ( 2 + 3 t ) - 4 =
W = 2 * 2 + 2 * 3 t - 4 =
W = 4 + 6 t - 4 =
W = 6 t
W = 6 t
L = 2 + 3 t
A = W * L =
A = 6 t * ( 2 + 3 t ) =
A = 6 t * 2 + 6 t * 3 t =
A = 12 t + 18 t ^ 2
t = 2
A = 12 t + 18 t ^ 2
A = 12 * 2 + 18 * 2 ^ 2
A = 24 + 18 * 4
A = 24 + 72
A = 96 cm ^ 2
A rectangle has sides of length x cm and 2x - 4cm and the length x cm at time t
seconds is given by x = 2 + 3t, (t >=0) . Show that the area, Acm2 , the rectangle, in
terms of t is A =12t + 18t^2 . Hence find the rate of change of the area at the instant when
t = 2.....
Please solve it........i can't understand this question properly.
2 answers
Picking up the equation found by Bosnian at
A = 12t + 18t^2
dA/dt = 12 + 36t ---> the instantaneous rate of change for any t
when t = 2
dA/dt = 12 + 36(2) = 84 cm^2/second
A = 12t + 18t^2
dA/dt = 12 + 36t ---> the instantaneous rate of change for any t
when t = 2
dA/dt = 12 + 36(2) = 84 cm^2/second
5 answers