1. Berdasarkan ide limit
$f'(x)=\lim_{h\to0}\left[\frac{f(x+h)-f(x)}{h}\right]$
Tentujan turunan pertama untuk masing-masing fungsi berikut.
a. $f(x)=3$
b. $f(x)=3x+2$
c. $f(x)=3x^2+4$
d. $f(x)=3x^2+2x+1$
Jawab:
a. $f(x)=3$ maka $f(x+h)=3$
$f'(x)=\lim_{h\to0}\left[\frac{f(x+h)-f(x)}{h}\right]$ maka
$f'(x)=\lim_{h\to0}\left[\frac{3-3}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{0}{h}\right]$
$f'(x)=\lim_{h\to0}0$
$f'(x)=0$
b. $f(x)=3x+2$
$f(x+h)=3(x+h)+2$
$f(x+h)=3x+3h+2$
$f'(x)=\lim_{h\to0}\left[\frac{f(x+h)-f(x)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{(3x+3h+2)-(3x+2)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{(3x+3h+2)-(3x+2)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{(3x+3h+2-3x-2)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{(3h)}{h}\right]$
$f'(x)=\lim_{h\to0}3$
$f'(x)=3$
c. $f(x)=3x^2+4$
$f(x+h)=3(x+h)^2+4$
$f(x+h)=3(x^2+2xh+h^2)+4$
$f(x+h)=3x^2+6xh+3h^2+4$
$f'(x)=\lim_{h\to0}\left[\frac{f(x+h)-f(x)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{(3x^2+6xh+3h^2+4)-(3x^2+4)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{(3x^2+6xh+3h^2+4-3x^2-4)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{(6xh+3h^2)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{h(6x+3h)}{h}\right]$
$f'(x)=\lim_{h\to0}6x+h$
$f'(x)=6x+0$
$f'(x)=6x$
d. $f(x)=3x^2+2x+1$
$f(x+h)=3(x+h)^2+2(x+h)+1$
$f(x+h)=3(x^2+2xh+h^2)+2(x+h)+1$
$f(x+h)=3x^2+6xh+3h^2+2x+2h+1$
$f(x+h)=3x^2+2x+1+6xh+3h^2+2h$
$f'(x)=\lim_{h\to0}\left[\frac{f(x+h)-f(x)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{(3x^2+2x+1+6xh+3h^2+2h)-(3x^2+2x+1)}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{6xh+3h^2+2h}{h}\right]$
$f'(x)=\lim_{h\to0}\left[\frac{h(6x+3h+2)}{h}\right]$
$f'(x)=\lim_{h\to0}6x+2+3h$
$f'(x)=6x+2+3(0)$
$f'(x)=6x+2$
Comments
Post a Comment