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Pre-Calculus Concepts Cheat Sheet (DRAFT) by

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Lines

Slope = m
Slope-­int­ercept: y=mx+b
m = dy/dx
Point-­slope: y-y1=m­(x-x1)
Parallel: m=m
General Form: Ax+By+C=0
Perpen­dic­ular: m=-(1/m)
Distance= sqr((x­2-x1)2+(y2-y1)2)

Absolute Values and Inequa­lities

Absolute Value is distance from 0
( = not included
labl=l­al*lbl
[ = included
la-bl=­lb-al
Infinities use ( in notation
Check inequality problems for both positive and negative answers, and that the answers make sense in original problem
Use number lines for systems of equations

Exponents

ax *ay = ax+y
ax / ay = ax-y
(ax)y=axy
(ab)x=ax * bx
(a/b)x = (ax/bx)
 

Functions

In functions, each x value has only one y value
Use vertical line test to determine if a graph shows a function
(f+g)(­x)=­f(x­)+g(x)
(f-g)(­x)=­f(x­)-g(x)
(fg)(x­)=f­(x)­*g(x)
(f/g)(­x)=­f(x­)/g(x), g(x)=0
(fg) =f(g(x))
For inverse functions, f(g(x))=x

Logarithms

Assume all these logs have a base of a
y=log(x) when ay=x
log(xy) = log(x)­+log(y)
log(x/­y)=­log­(x)­-log(y)
log(x)n=n*log(x)
log(1)= 0, log(a)=1

Natural Log and e

ln and e are inverse operations and cancel each other out
ln(xy)­=ln­(x)­+ln(y)
ex * ey =ex+y
ln(x/y­)=l­n(x­)-ln(y)
ex \ ey =ex-y
ln(x)n=n*ln(x)
(ex)y= exy
Change of Base: log(base a)(x) = ln(x)/­ln(a)
 

Trigon­ometric Functions and Graphs

Function
Graph Descri­ptions
(Without Transf­orm­ations)
sinx= O/H
Sinuso­idal, Starts at 0
cosx= A/H
Sinuso­idal, Starts at A
tanx= O/A
Positive cubic functions
cscx= H/O
Positive and Negative Parabolas
(Starts at 0)
secx= H/A
Positive and Negative Parabolas
(Doesn't start at 0)
cotx= A/O
Negative cubic functions
Trig functions take an angle and find the corres­ponding ration of the sides
Inverse functions take the ration of the sides and find the corres­ponding angle

Graphs

Increa­sing: m>0
Decrea­sing: m<0
Constant: m=0
Minimum: Decreasing to Increasing
Maximum: Increasing to Decreasing