Derivative of sqrt(x)7
Airman said:
The derivative of
y = x (1/2)
is
y’ = (1/2)x(-1/2)
Airman and Cr6, can you show in brief detail how to get that answer (y' = (x/2)^-1/2) from Mathis' method?
First, Miles said (probably in calcsimp, forgive me if I paraphrase), "Everyone fails calc-1 (and two), even nerds. Someone who can memorize formulas without trying to understand them may do well, but everyone else fails it." It boils down to the fact that calculus is described in infinitesimals, and infinitesimals really don't exist. So calculus is a sort of a gateway math where you have to give up some of your physical certainty and just calculate. This table, however, is something else. It's easy to interpret, while rich in all the possibilities of higher power functions. Spend some time reading his papers and studying his table and you will understand calculus. Well, a lot more than most mathematicians currently do.
Miles' original calculus paper: A Re-definition of the Derivative (why the calculus works—and why it doesn’t.
http://milesmathis.com/are.html
Miles' simplified calculus paper:
http://milesmathis.com/calcsimp.html
I'll start where the table has been trimmed down to to show the relationship between the exponential curve and the rate of change of that exponential curve
2x = Δx2
3x2 = Δx3
4x3 = Δx4
5x4 = Δx5
6x5 = Δx6
The last part just needs to be reversed to
Δx2 = 2x
Δx3 = 3x2
Δx4 = 4x3
Δx5 = 5x4
Δx6 = 6x5
The rate of change, Δ, of x to the nth power, equals n times x to the (n-1) power, Δy^n = y’ = nx^(n-1).
The assignment is to find the derivative of sqrt(x).
Find y' when: y = x^(1/2).
We are given, n = (1/2), so,
y’ = nx^(n-1)
y' = (1/2)x^((1/2)-1)
y' = (1/2)x^(-1/2)
Also, would either of you like to quote briefly from Mathis' papers (such as where links are given above by Airman) to show a little about how he solves log(x), sin(x) etc? Does he solve them by finding constant differentials as above?
David, Take note. Miles has created new tables, and, every function doesn't necessarily require a new table. New tables (I think) include: ln (x), 1/x, and e.
I've cited the MM papers, multiple times. You're making arguments without support. I'll look at your assertion concerning the derivative of (sin(x))^2, even though Miles makes the substitutions I mention below.
In " Trig Derivatives foundwithout the old Calculus",
http://milesmathis.com/trig.html, Miles starts with,
y = sin x = ±√(1 - cos2 x) , then substitutes
y = a = ± (1- b^2)^(1/2)
And then uses the table already described. He differentiates both a and b to get:
y' = b = cos x
In "My Calculus Applied to Exponential Functions",
http://milesmathis.com/expon.html, Miles uses both the table already given as well as a new table listings for e. The notion that a new table is necessary for each function is false.
In, " The Derivatives of the Natural Log and 1/x are wrong",
http://milesmathis.com/ln.html, Miles makes new ln (x) and 1/x tables.
David said Mathis' method is:
x: 1, 2, 3, 4, 5
sqrt(x): 1, 1.414, 1.732, 2, 2.236
∆sqrt(x): 0.414, 0.316, 0.268, 0.236
∆∆sqrt(x): -0.098, -0.048, -0.032
∆∆∆sqrt(x): 0.05, 0.016
∆∆∆∆sqrt(x): -0.034
Nope. I disagree. This is David's table, far as I know.
The triangles mean "delta" which I think means "rate of change of". Right?
And "rate of change of" means the rate at which the differences between integer values of x increase or decrease. Right?
I would say, "... differences between EXPONENTIAL values of x increase or decrease.
Does David's table indicate that the sqrt(x) never comes to a constant difference between values of x?
Or does it show that the constant difference is -.034 at the fourth level?
Can each of the lines of text in David's table be shown on a graph, if y = sqrt(x)?
There are no constant differentials in that table. It's not Mile's table. It has only one "variable". Why would we need a new exponential table when we already have one?
Is the Derivative the Slope of the Tangent to a Curve?
Here's a graph of y = x^2 {y = x squared}, y = x {the diagonal dashed line}, and y = x^1/2 {y = square root of x, shown as x = y^2, which is the same}.
Image
Does the derivative mean the slope of the tangent to a curve?
That's what we've been taught, but there are several problems with comparing lines on graphs to reality, especially at "points" in reality or on the curve.
Distance, velocity, acceleration, and changing acceleration of any order represent the sort of varying behavior that calculus was intended to describe.
So, Yes! (I think). That's all for now.
REMCB