Question: Functions & Chain Rule

Hi,

I was hoping someone can tell me if there's a better way for doing this math.

I think i was doing this wrong so i posted the full results. The answers r correct but i might be doing this the long way.

Thanks in Advance.
 

Section 1.6: Combinations of Functions

 

Example 1: - Sum Rule

"ex1f(x):= 2 x+1"

proc (x) options operator, arrow, function_assign; 2*x+1 end proc

(1)

"ex1g(x):=x^(2)+2 x-1"

proc (x) options operator, arrow, function_assign; x^2+2*x-1 end proc

(2)

ex1f(x)+ex1g(x)

x^2+4*x

(3)

eval(x^2+4*x, [x = 2])

12

(4)

 

Example 2: - Difference Rule

"ex2f(x):=2 x+1"

proc (x) options operator, arrow, function_assign; 2*x+1 end proc

(5)

"ex2g(x):=x^(2)+2 x-1"

proc (x) options operator, arrow, function_assign; x^2+2*x-1 end proc

(6)

ex2f(x)-ex2g(x)

-x^2+2

(7)

eval(-x^2+2, [x = 2])

-2

(8)

Example 3: - Product Rule

"ex3f(x):=x^(2)"

proc (x) options operator, arrow, function_assign; x^2 end proc

(9)

"ex3g(x):= x-3"

proc (x) options operator, arrow, function_assign; x-3 end proc

(10)

ex3f(x)*ex3g(x)

x^2*(x-3)

(11)

collect(x^2*(x-3), x)

x^3-3*x^2

(12)

eval(x^3-3*x^2, [x = 4])

16

(13)

Example 4: - Quotient Rule

"ex4f(x):=sqrt(x)"

proc (x) options operator, arrow, function_assign; sqrt(x) end proc

(14)

"ex4g(x):=sqrt(4-x^(2))"

proc (x) options operator, arrow, function_assign; sqrt(4-x^2) end proc

(15)

ex4f(x)/ex4g(x)

x^(1/2)/(-x^2+4)^(1/2)

(16)

 

Example 5: - Composition - Chain Rule

 

This is an example of the chain rule.

"ex5t1(x):=sqrt(x):"

"ex5t2(x):=x-1:"

Function in another function:

 

ex5t1(ex5t2(x))

(x-1)^(1/2)

(1.1)

eval((x-1)^(1/2), [x = 2])

1

(1.2)

plot((x-1)^(1/2))

 

Example 6: - Composition - Chain Rule

 

Insert*two*functions

 

"ex6f(x):=x+2:"

"ex6g(x):=4-x^(2):"

 

ex6f(ex6g(x))

-x^2+6

(2.1)

eval(-x^2+6, [x = 0])

6

(2.2)

eval(-x^2+6, [x = 1])

5

(2.3)

``

ex6g(ex6f(x))

4-(x+2)^2

(2.4)

eval(4-(x+2)^2, [x = 0])

0

(2.5)

eval(4-(x+2)^2, [x = 1])

-5

(2.6)

``

Example 7: Find Domain with Chain Rule

 

Insert two Functions:

"ex7f(x):=x^(2)-9:"

"ex7g(x):=sqrt(9-x^(2)):"

``

ex7f(ex7g(x))

-x^2

(3.1)

plot(-x^2)

 

[-3, 3]

[-3, 3]

(3.2)

``


 

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