Some useful formulas for 408K
The pythagorean theorem :
This is a handy tool for any problem that involves right triangles. It says that a^2+b^2=c^2.
Example:
If you have a right triangle with where the two legs are 3 and 4, what is the hypotenuse?
Here a =3 and b=4 so a^2+b^2=3^2+4^2=9 + 16=25=c^2. So c=5.
Algebra rules used in 408K
a^2-b^2=(a-b)(a+b)
This is a handy rule that works both ways so you could also say:
(a-b)(a+b)=a^2-b^2
Examples:
(x+5)(x-5)= x^2-25
Factor 4y^2-1:
Here a^2 = 4y^2 so a could be 2y and b^2=1 so b could be 1.
So we get:
4y^2-1=(2y-1)(2y+1)