Quote:
Originally Posted by Crafty  Well, I start school tomorrow, and I need some help finishing this.
It is mostly pre-calc. stuff.
f(x)= {(3,5), (2,4), (1,7)}
g(x)= square root of x-3
h(x)= {(3,2), (4,3), (1,6)}
k(x)= x^2 + 5
So, with that information what would (f + h)(1) = ?
How would I go about doing that?
What do I add?
What does the 1 stand for? |
Basically, whenever you have something in the form of f(x) = 4x, find f(1), it means you substitute 1 in for x. Therefore when you have (f + g)(1), add f and g together, then substitute x=1 into the equation to find your answer.
Quote:
|
Originally Posted by Crafty Another one.
Expand (x+y)^3
I just don't remember how to expand. |
For this one, there's two methods.
First, use something called Pascal's Triangle. Here it is:
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
.
.
.
What this means is that your exponent corresponds to the second number in each row, then those are your coefficients. Therefore, (x + y)^3 =
1(x^3) + 3(x^2) y + 3x(y^2) + 1(y^3).
So start with x's as your high exponent, then reduce it by one every time you go to the next number.
The other way is to use combinations. In your calculator, go to the section with probability, and this time you will use the nCr tool. To find the coefficients, do the following:
3nCr0, 3nCr1, 3nCr2, 3nCr3. You use three because it's the exponent. Then follow the method of reducing exponents by one for x every time and increasing by one for y every time.