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Mathematics (basic Differentiation Class And Skill) - Education - Nairaland

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Mathematics (basic Differentiation Class And Skill) by thankyouJesus(m): 6:49pm On Mar 27, 2015
Good afternoon all, in a bid to contribute my own quota to "our" admission, I will be treating some MATHEMATICS topics/questions [I am not promising to be online 24/7, but when tides favour the ocean].
Some of the topics "we" will be considering are, in no particular order:
1. Calculus.
2. Trigonometry.
3. Number base.
4. Co-ordinate geometry.
5. Polynomial.
6. Statistics.
7. Matrices.
8. Algebra.
9. Probability.
10. E.t.c.
For any questions/suggestions/observations/e.t.c, please do make it before the first class [23/03/2015].
Note
1. There is no guaranty any of the topics will be among the post utme questions, therefore, I am not liable for any feeling/opinion/e.t.c that may arise from this.
2. I will try my best to make the topics/questions easy to understand, but, typing mathematical symbols/expressions in an online forum is not going to be easy.
3. The fruitfulness of this class depends on my schedule, i.e I can't guaranty everyday lectures.
Vote of thanks:
Mr. Dopeyomi, thank you for this inspiration.
Once again, Happy Sunday to you all.
22nd March, 2015.
13:30:59PM.
Re: Mathematics (basic Differentiation Class And Skill) by thankyouJesus(m): 6:53pm On Mar 27, 2015
Good evening all, as per my obligation, today will be "our" first class. "We" will be considering differentiation.
Note 1:
1. dy/dx can also be represented as y'.
2. d2y/dx2can also be represented as y", till infinity.
3. d/dxmeans "we" are differentiating with respect tox, d/dumeans we are differentiating with respect to . . . . . . . . . . . .very good, u.
4. wrt means with respect to.
DIFFERENTIATION.
Differentiation means rate of change.
General formula:
if y = axn,
a is the co-efficient of x.
n is the power of x.
Therefore, dy/dx = power "times" co-effecient of x "times" the power of x "minus" 1.
Mathematically,
y = axn,
dy/dx = naxn - 1.
-----------------------------
Example 1. Find y' [it also means dy/dx] if y = 2x.
Solution:
the co-efficient of x is 2.
The power of x is 1.
Therefore,
y = 2x
dy/dx = (1)(2)x1-1
dy/dx = 2x0
dy/dx = 2(1)
because x0is 1.
dy/dx = 2.
-----------------------------.
Example 2: find y' if y = 3x4.
Solution:
y = 3x4
y = 12x3
-----------------------------.
Example 3: find y' if y = x
.
.
.
.
.
.
.
y' = 1.
Very good, because,
y = x
the co-efficient of x is 1.
The power of x is 1.
Therefore,
y = x
y' = (1)(1)x1-1
y' = 1x0
y' = 1(1)
y' = 1.
-----------------------------.
Example 4: find y' if y = 2.
Solution:
y = 2,
the question can also be changed into
y = 2(1)
it can be further changed into
y = 2(x0)
since,
y = 2x0
y' = (0)(2)x0-1
y' = 0x-1
y' = 0.
Note 2: The derivative of a constant is 0.
i.e
d/dx (7) = 0
d/dx (10) = 0, but,
d/dx (7x) = 7
d/dx (10x) = 10.
-----------------------------.
Summary:
1. Differentiation means rate of change.
2. If y = axn, then dy/dx = naxn-1.
3. The differentiation of constant values is 0. E.g,
y = 6,
dy/dx = 0,
y = 1000000000
dy/dx = 0.
-----------------------------.
Assignment: find dy/dx if y =
1. 20x
2. -50x3
3. -25x-2
4. 30/x2, [Hint: 1/x2is x-2].
Any question?
Good night class.
23rd March, 2015.
21:35:45
Re: Mathematics (basic Differentiation Class And Skill) by thankyouJesus(m): 6:58pm On Mar 27, 2015
Good morning to you all, how was the night?
Yesterday, we were considering differentiation, we were able to conclude that:
1. Differentiation means rate of change.
2. If y = axn, then dy/dx = naxn-1.
3. The differentiation of a constant is zero.
Today, we will be considering another aspect of differentiation.
DIFFERENTIATION OF POLYNOMIALS.
To differentiate a polynomial, we differentiate each term in turn.
General form:
if y = axb+ cxd+ exf+ . . .,
then dy/dx = baxb-1+ dcxd-1+ fexf-1+ . . ..
. . . . . . . . . . . . . . . . . . . . . . . .
Example 1: if y = x4+ 5x3- 4x2+ 7x - 2.
Solution:
dy/dx = (4)(1)x4-1+ (5)(3)x3-1- (4)(2)x2-1+ (7)(1)x1-1- 0.
dy/dx = 4x3+ 15x2- 8x + 7.
. . . . . . . . . . . . . . . . . . . . . . . .
Example 2: if y = 2x5+ 4x4- x3+ 3x2- 5x + 7, find an expression for dy/dx and the value of dx/dx at x = 2.
Solution:
So, first of all,
dy/dx =
.
.
.
.
.
.
.
Very good, because, if
y = 2x5+ 4x4- x3+ 3x2- 5x + 7.
Then,
y' = 10x4+ 16x3- 3x2+ 6x - 5.
Substituting x = 2, we have,
y' = 10(2)4+ 16(2)3- 3(2)2+ 6(2) - 5.
Therefore,
y' = 283.
. . . . . . . . . . . . . . . . . . . . . . . .
Example 3:
if y = 2x2- 5x + 3, then
dy/dx = 4x - 5.
This double statement can be written as a single statement by putting 2x2- 5x + 3 in place of y in dy/dx. i.e
d/dx (2x2- 5x + 3) = 4x - 5.
. . . . . . . . . . . . . . . . . . . . . . . .
Example 4:
In the same way,
d/dx (4x3- 7x2+ 2x + 3) =
Solution:
12x2- 14x + 2.
Note: Either of the two methods is acceptable: it is just a case of which is the more convenient in any situation.
. . . . . . . . . . . . . . . . . . . . . . . .
Summary:
1. To differentiate a polynomial, we differentiate each term in turn.
2. if y = axb+ cxd+ exf+ . . .,
then dy/dx = baxb-1+ dcxd-1+ fexf-1+ . . ..
. . . . . . . . . . . . . . . . . . . . . . . .
Assignment:
1. No 39, 1994.
If y = 3t3+ 2t2- 7t + 3, find dy/dt at t = -1.
(a) -1 (b) 1 (c) -2 (d) 2.
2. No 19, 2002.
If y = x2- 1/x, find dy/dx
(a) 2x + 1/x2(b) 2x + x2(c) 2x - 1/x2(d) 2x - x2
3. No 36, 2008.
Find the derivative of y = x7- x5
(a) x (x2 - 1) (b) 3x (x[sup]2- 1) (c) 3x2- 1 (d) 7x6- 5x4.
. . . . . . . . . . . . . . . . . . . . . . . .
Things to note before the next class:
1. There is difference between
(a) sinx - cosx
(b) sinx + cosx
(c) sinx cosx,
the difference is, (a) &(b) are polynomials because they are connected by either + or - while (c) is connected by multiplication. Another method is used to solve c.
2. If y = sinx, dy/dx = cosx.
3. If y = cosx, dy/dx = -sinx.
Have a splendid day.
Any question?
24th March, 2015.
07:07:33
Re: Mathematics (basic Differentiation Class And Skill) by thankyouJesus(m): 7:02pm On Mar 27, 2015
Good evening all, how is your day fairing?
In our last class, we were considering differentiation of polynomials. We were able to achieve that
1. To differentiate a polynomial, we differentiate each term in turn.
2. If y = axb+ cxd+ . . ., then, dy/dx = baxb-1+ dcxd-1+ . . ..
Now, we will be considering a different aspect:
HIGHER DERIVATIVES.
If y = 2x4- 5x3+ 3x2- 2x + 4, then, by the previous method:
dy/dx = 8x3- 15x2+ 6x - 2.
This expression for dy/dx is itself a polynomial in powers of x and can be differentiated in the same way as before, i.e. we can find the derivative of dy/dx.
d/dx [dy/dx] is written d2y/dx2and is the second derivative of y wrt x (spoken as "dee two y by dee x squared".
So, in this example, we have:
y = 2x4-5 x3+ 3x2- 2x + 4.
dy/dx or y' = 8x3- 15x2+ 6x - 2.
d2y/dx2or y" = 24x2- 30x + 6.
We could, if necessary, find the third derivative of y in the same way:
d3y/dx3or y"' = . . . . . . . . . .
.
.
.
Very good,
y"' = 48x - 30
. . . . . . . . . . . . . . . . . . . . . . . . Summary:
if y = axb+ cxd+ exf+ gxh+ . . .
Then,
dy/dx = baxb-1+ dcxd-1+ fexf-1+ hgxh-1+ . . .
Also,
y" = (b-1)baxb-1-1+ (d-1)dcxd-1-1+ (f-1)fexf-1-1+ (h-1)hgxh-1-1+ . . .
. . . . . . . . . . . . . . . . . . . . . . . .
Things to note before next class:
1. Y = sinx
dy/dy = cosx
2. Y = cosx
dy/dx = -sinx
3. Y = tanx
dy/dx = sec2x.
. . . . . . . . . . . . . . . . . . . . . . . .
Assignment:
Pick up JAMB mathematics past question and solve anything "solvable" in differentiation.
Any question?.
Have a blissful night rest.
24th March, 2015.
19:22:36
Re: Mathematics (basic Differentiation Class And Skill) by Avast(m): 7:49pm On Mar 27, 2015
GOOOOOOOOOD WORK
Re: Mathematics (basic Differentiation Class And Skill) by Nobody: 7:54pm On Mar 27, 2015
this is so cool man!!I'm loving Maths.
Re: Mathematics (basic Differentiation Class And Skill) by Girltee1(f): 9:10pm On Mar 27, 2015
Nice job, man.smiley
Re: Mathematics (basic Differentiation Class And Skill) by thankyouJesus(m): 11:45pm On Mar 27, 2015
shadowgwalker:
this is so cool man!!I'm loving Maths.
Avast:
GOOOOOOOOOD WORK
Girltee1:
Nice job, man.smiley
check the UI 2015/2016 for current update or better still, you can follow me to be updated.
Re: Mathematics (basic Differentiation Class And Skill) by thankyouJesus(m): 1:51pm On Mar 03, 2016
I need to continue this, not for JAMBITES but to stimulate interest and reduce anxiety.

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