thushanthan said:
But I have no idea why it is called as Single Variable & Multi Variable ?
In Cal - I we use something like y=x2+20x+100; It involves two variables X and Y. Then why
we call it as Single Variable? One of my friend told that in Multi variable I will be learning to do Calculus with
Vectors and Matrices. Also I have to plot graphs in 3 Dimension. Is it true? Can anyone explain this to me ??
Thanks in advance.
Let's consider the function you suggested: f(x) =x
2+20x+100.
We call this function "single-variable" because it DEPENDS one one variable. You've probably heard "x" and "y" referred to as the "dependent" and "independent" variables (respectively).
You are actually already familiar with multivariable functions (functions that DEPEND on
more than one variable). Think about a restaurant that sells burgers, chips, and drinks. We can call these variables b, c, and d. The amount of income/revenue for the restaurant depends on how many burgers, chips, and drinks they sell. If the prices are $4, $1, and $2, an appropriate function for r (the revenue) would be:
r(b,c,d) = 4b + 1c + 2d.
Here's what you AREN'T used to:
In the xy plane, you can graph the parabola that we started with. The x-coordinates come from the DOMAIN, and the Y-coordinates come from the RANGE.
You can still graph a function like g(x,y) (=z). The x AND y coordinates come from the domain, while the z-coordinate comes from the RANGE.
With more than 2 independent variables, it's actually IMPOSSIBLE to graph the domain and range. There are these things called level curves and slope fields and all sorts of fancy-pants stuff, but we can cross that bridge when we get to it.
As for your other questions:
Vectors can have one, two, or MORE dimensions. The matrix component of many multivariable courses is minimal. You could spend a half hour learning about the dimensions of matrices, matrix multiplication, and determinants, and that might get you through.