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AP Calculus

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Special Focus: The Fundamental<br />

Theorem of <strong>Calculus</strong><br />

Solutions<br />

1. (a) Using the FTC, the derivative of S(x) is the integrand evaluated at x:<br />

⎛ π x<br />

S '( x)<br />

= sin⎜<br />

⎝ 2<br />

2<br />

⎞<br />

⎟ .<br />

⎠<br />

(b) Technology produces the following graph of y = S"(x).<br />

Notice that the graph oscillates faster and faster as |x| increases. By using a<br />

calculator to find the zeros, students might recognize the numerical<br />

approximations for ± 2k . The zeros of S′<br />

( x) are 0,± 2,± 4, ± 6,....<br />

By hand, students can set S′ ( x) = 0 and continue in the following manner:<br />

⎛<br />

sin π x2 ⎞<br />

⎜ ⎟ = 0<br />

(Use the expression for S′<br />

( x).)<br />

⎝ 2 ⎠<br />

π x<br />

kπ<br />

2 = (Set the argument equal to kπ.)<br />

x<br />

2<br />

= ± 2 k<br />

(Solve for x.)<br />

x = 0, ± 2, ± 4, ± 6, ... (Let k = 0, 1, 2, 3, ....)<br />

116<br />

<strong>AP</strong>® <strong>Calculus</strong>: 2006–2007 Workshop Materials

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