quiz7.mws

MCS 320 Quiz 7 Friday 14 October 2005

> restart;

1. Show that

                 n

              ----               1

             >        k^3 = --- n^2 (n+1)^2

              ----              4

               k=1

ANSWER :

> s := sum(k^3,k=1..n);

s := 1/4*(n+1)^4-1/2*(n+1)^3+1/4*(n+1)^2

> factor(s);

1/4*n^2*(n+1)^2

2. Give the Maple command to define the function defined by the integral of sin(x^2) for x from 0 to t.

   For any number t, the function should return a floating-point approximation (precision depending on Digits) for f(t).

   Give the Maple command to compute the derivative function f'.  What is f'(2)?

ANSWER :

> f := t -> evalf(Int(sin(x^2),x=0..t));

f := proc (t) options operator, arrow; evalf(Int(sin(x^2), x = (0 .. t))) end proc

> f(2);

.8047764893

> Df := D(f);

Df := proc (t) options operator, arrow; evalf(sin(t^2)) end proc

> Df(2);

-.7568024953