SAT math

Quadratic sum of roots

-b/a

Quadratic product of roots

c/a

Discriminant

b²-4ac

Discriminant answers meanings

pos: 2

=0: 1

neg: no real solutions

Growth and Decay Formula

y=a(1± r)^t

a=initial, r=rate, t=time

radioactive decay, populating growth, compound interest

Standard Form Slope

-A/B

Standard Form y-int

C/B

Standard Form x-int

C/A

When given 2 equations with infinitely many solutions…

find a way to make them equal

2 equations with no solution are…

parallel

Arithmetic mean

average

Formula for arithmetic mean

T=AN; total = average x number of things

Median

number in the middle, if there’s an even amount of numbers, median=average of the two middle numbers

Mode

number that appears the most

Range

difference between greatest and least number in list

Standard deviation

measure of the spread of a group of numbers around the mean

ex) more spread out → larger SD, less spread out —> smaller SD

Probability of x

number of outcomes that give what you want/total number possible outcomes

% inc/dec, %change

(new-original/original)*100

Arc length formula

s=rtheta; arc length=radiusxcentral angle in radians

part/whole=

central angle/360 degrees=arc length/2pir=sector area/pir²