68
This average, which is called the
central difference
, is expressed as:
uu
uu
uTo perform a differential calculation
Example To determine the derivative at point x = 3 for the function
y = x
3
+ 4 x
2
+ x – 6, when the increase/decrease of x is defined as
$x = 1E – 5
Input the function
f(x).
AK4(CALC)2(d/dx)
vMd+evx
+v-g,
Input point
x = a for which you want to determine the derivative.
d,
Input $
x, which is the increase/decrease of x.
bE-f)
w
• In the function f(x), only X can be used as a variable in expressions. Other vari-
ables (A through Z, r,
#
) are treated as constants, and the value currently as-
signed to that variable is applied during the calculation.
• Input of $
x and the closing parenthesis can be omitted. If you omit $x, the calcu-
lator automatically uses a value for $x that is appropriate for the derivative value
you are trying to determine.
• Discontinuous points or sections with drastic fluctuation can adversely affect pre-
cision or even cause an error.
1 f (a + $x) – f (a) f (a) – f (a – $x)
f '(a) = ––
––––––––––––– + –––––––––––––
2 $x $x
f (a + $x) – f (a – $x)
= –––––––––––––––––
2$x
3 - 3 Differential Calculations
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