Nothing Special   »   [go: up one dir, main page]

Md. Aktar Kamal Assistant Professor (Management) FBS, Bup

Download as pptx, pdf, or txt
Download as pptx, pdf, or txt
You are on page 1of 20

DIFFERENTIAL

CALCULUS

Md. Aktar Kamal


Assistant Professor ( Management)
FBS,BUP
DIFFERENTIAL CALCULUS

CALCULUS gives us the technique for


measuring changes in the dependent
variable with the reference to a very small
change, approaching almost zero, in the
independent variables or variables
DIFFERENTIAL CALCULUS
The techniques concerning the calculation of
the average rate of change are studies under
differentiation or the Differential Calculus and
the calculation of the total amount of change
in the given range of values is studied under
integration or integral Calculus.
DIFFERENTIAL CALCULUS
Let us assume that y has been produced by
labor x and that as we increase x (labor) by
one unit, the amount of y increases by four
units. This relationship is shown by y = 4x
DIFFERENTIAL CALCULUS
When x is increased by a small increment Δx, then y
increases by Δy, and
we have y + Δy = 4(x +Δx) = 4x + 4Δx = y + 4Δx
⇒ Δy = 4Δx
⇒ Δy /Δx = 4
Δy /Δx is the incremental ratio of dependent variable y
with respect to the independent variable x , i.e. we can
say Δy /Δx is the change in y with respect to a small unit
change in x.
Rules

(1) (xn ) = n xn-1


(2) (k) = 0 Where k is a constant, i.e. The derivative of a
constant is 0.
(3) [ kf(x)]= k [f(x)]= kf/(x) Where k is a constant.
(4) [ f(x) ±g(x)] = f(x) ± g(x)
(5) [ f(x) g(x)] = f(x) [g(x)] + g(x) [f(x)]
(6) If y = u/v then = where v ≠ 0.
(7) If y = x then (x) = 1
Rules –
Rules
Rule – 1: ( xn ) = n xn-1
Find the first derivative of the following function? if
(a) f(x)= x10
(b) f(x)= x 2/3 (c) f(x) =
Solution: (a) Given f(x) = x10
Differentiating w. r. t. ‘x’ then we have
∴ f(x) = (x10 ) = 10 x10-1 = 10 x9 ∴ f/(x)
= 10 x9
Rules
Rules
If g(x) = x find g /(x)
 
Solution : Given g(x) = x6.5
∴ g(x) = ( x 6.5) = 6.5 X5.5
∴ g/(x) = 6.5 x 5.5
Rules

Rule – 2: If k is any constant then (k) = 0


Example: If f(x) = 10 then f(x) = (10) = 0
Rules
Rule-3: [k f(x)] = k [f(x)]= k f/ (x)
Where k is a constant.
Example:
(a) If y = 2x then find =?
Solution:
Given y = 2x
Differentiating w. r. t. ‘x’ then we have
∴ (y) = (2x) = 2 (x) = 2 × 1 = 2
∴ y1 = 2
Rules
(b) If y = 3x2 then find =?
Solution:
Given y = 3x2
Differentiating w. r. t. ‘x’ then we have
∴ (y) = (3x2 ) = 3 (x2) = 3 ×2 x = 6x
 
Rules
� Rule -4: [ f(x) ±g(x)] = f(x) ± g(x)
 
Example: If y = 5x4 + 3x2 + 2x +7 then find y .
 
Solution:
Given
y = 5x4 + 3x2 + 2x +7
Differentiating w. r. t. ‘x’ then we have
∴ ( y ) = (5x4 + 3x2 + 2x +7)
(y) = (5x4) + (3x2) + (2x) + (7)
y = 5 (x4) + 3 (x2) + 2 (x) + (7)
y = 20 x3 + 6 x + 2 .1 +0
=20 x3 + 6x + 2 (Ans.)
Rules
�Problem:
(i) If y = 2 x - 4 x3 + 5x – 10 then find y .
(ii) If y = 7q3 – 4p2q2 +3q then find = ?
 
Rules
� Rule -5(Product rule): [ f(x) g(x)] = f(x) [g(x)] + g(x)
[f(x)]
 
Example – (i) If f(x) = (x2)(x3) then find f1(x) .
 
Solution:
Given f(x) = (x2)(x3)
Differentiating w. r. t. ‘x’ then we have
∴ f(x) = (x2)(x3)
= x2 x3 + x3 x2 = x2 × 3 x2 + x3 × 2x = 3x4 + 2x3
 
Rules

�Find the derivative of i)g(x)=(2x-7)10


ii)g(x)=(3x2 -2x+5)3/2
Rules
(ii) If f(x) = (x2 +3)(2x + 5)3/2 then find f1(x).
 
Solution:
Given f(x) = (x2 +3)(2x + 5)3/2
Differentiating w. r. t. ‘x’ then we have
∴ f(x) = (x2 +3)(2x + 5)3/2
= (x2 +3) (2x + 5)3/2 + (2x + 5)3/2 (x2 +3)
= (x2 +3) (2x + 5)3/2 (2x+5) + (2x + 5)3/2 [ (x2) + (3) ]
= (x2 +3) (2x + 5) [ (2x) + (5)] + (2x + 5)3/2 (2x +0)
= (x2 +3 )(2x + 5) (2 +0) + 2x (2x + 5)3/2
= 3(x2 +3 )(2x + 5) + 2x (2x + 5)3/2
Rules
Rules

You might also like