View Full Version : Delta symbol means what?
leebaseball50
Aug 11, 2007, 02:29 PM
g(x)=x^2+3x-1
find (g(x+(delta symbol)x) - g(x)) / ((delta sym)x)
how do I solve this? Please help me!
does the delta symbol mean change in this case? I don't no what to do :(:confused: :mad:
galactus
Aug 11, 2007, 04:25 PM
Yes, delta means the 'change in x'. This is the definition of a derivative.
There should be a graph in your calculus book which will help show you what this means.
Except, most times, h is used instead if delta(x). I will use h.
It's based on the slope of a line. The instantaneous rate of change of y with respect to x at
a point x_0 is:
slope=m=\lim_{x_{1}\to\(x_{0})}\frac{f(x_{1})-f(x_{0})}{x_{1}-
x_{0}}
x_{1}-x_{0}=h. Then, x_{1}=x_{0}+h and h approaches 0
as x_{1} approaches x_{0}. Then we can write the slope of
the line as m=\lim_{h\to\0}\frac{f(x_{0}+h)-f(x_{0})}{h}
I will show you how this works and you try another. OK?
\lim_{h\to\0}\frac{f(x+h)-f(x)}{h}
Wherever you have an x, insert x+h. f(x+h)=(x+h)^{2}+3(x+h)-1
You have \lim_{h\to\0}\frac{[(x+h)^{2}+3(x+h)-1]-[x^{2}+3x-1]}{h}
Which simplifies to(you can do the algebra):
\lim_{h\to\0}\frac{2xh+h^{2}+3h}{h}
Now, what do you have as h approaches 0? The derivative of x^{2}+2x-1
Toms777
Aug 11, 2007, 04:26 PM
g(x)=x^2+3x-1
find (g(x+(delta symbol)x) - g(x)) / ((delta sym)x)
how do i solve this? please help me!
does the delta symbol mean change in this case? i don't no what to do :(:confused: :mad:
Delta is a Greek letter that looks like a triangle on its base. This is one: Δ
Tom