Cheat sheet

NY Regents Algebra I Cheat Sheet

Algebra (Equations)

48-61%of exam

QuadraticsFactoringLinesSystemsInequalitiesMethod Pickers

Functions

24-32%of exam

NotationDomain + RangeExponentialSequencesTransformationsFunction Type

Number + Statistics

11-25%of exam

CorrelationResidualsTwo-Way TablesCenter + SpreadReal vs Irrational

Exam Skills

10-15%of exam

ModelingInterpret in ContextReference SheetShow Work

Quick Facts

Exam
Regents Algebra I
Standards
Next Generation Math
Questions
35 in 4 parts
Time
3 hours
Pass
Scale score 65
Calculator
Graphing allowed
Reference sheet
Provided
Max credits
82 raw

Order of Operations

PEMDAS: Please Excuse My Dear Aunt Sally

ParenthesesExponentsMultiply/DivideAdd/Subtract

Factoring vs Formula

Factoring

  • Nice integers
  • Zero product
  • Fast

Quadratic formula

  • Any quadratic
  • Uses discriminant
  • Always works

Easy vs universal

Solve Quadratic How?

  1. Factors easilyFactor + zero product(Fastest)
  2. a = 1, b evenComplete the square(Clean)
  3. Will not factorQuadratic formula(Always works)
  4. Need only rootsGraph x-intercepts(Calculator)
  5. x^2 = numberSquare root both sides(Two roots)
  6. Need vertexVertex form / -b/2a(Min or max)

Quadratic Core

Standard form
y = ax^2 + bx + c
Quadratic formula
x = (-b +/- root) / 2aReference
Discriminant
b^2 - 4ac
Axis of symmetry
x = -b / 2a
Vertex x
-b / 2a
Vertex form
a(x-h)^2 + k
Vertex point
(h, k)
Zeros
Where y = 0

Quadratic Formula

x = (-b +/- root b^2 - 4ac) / 2a

a, b, c from standard+/- gives two rootsInside = discriminant

Solve System How?

  1. One variable aloneSubstitution(Plug in)
  2. Opposite coefficientsElimination(Add equations)
  3. Answer choices givenGraph intersection(Calculator)
  4. Variables cancel falseNo solution(Parallel)
  5. Variables cancel trueInfinite solutions(Same line)

Discriminant Rules

b^2 - 4ac > 0
Two real roots
b^2 - 4ac = 0
One real root
b^2 - 4ac < 0
No real roots
Perfect square
Two rational roots
Not a square
Two irrational roots
Sum of roots
-b / a
Product of roots
c / a

Factoring Patterns

GCF first
Pull common factor
Diff of squares
a^2 - b^2 = (a-b)(a+b)
Perfect trinomial
a^2 + 2ab + b^2
x^2 + bx + c
Multiply c, add b
ax^2 + bx + c
AC method / split
Zero product
Each factor = 0
Complete square
Add (b/2)^2

Linear Forms

Slope
(y2 - y1)/(x2 - x1)
Slope-intercept
y = mx + b
Point-slope
y-y1 = m(x-x1)
Standard form
Ax + By = C
y-intercept
b, where x = 0
Parallel
Same slope m
Perpendicular
Negative reciprocal slope
Horizontal
Slope = 0

Systems + Inequalities

Substitution
Plug one into other
Elimination
Add to cancel variable
Graphing
Solution is intersection
No solution
Parallel, no cross
Infinite solutions
Same line
Flip sign
Divide by negative
Dashed line
Strict < or >
Solid line
<= or >=

Line Equation

y = mx + b: slope m, intercept b

m = rise/runb = where x is 0+m up, -m down

Linear vs Exponential

Linear

  • Add constant
  • Constant rate
  • Straight line

Exponential

  • Multiply constant
  • Constant ratio
  • Curved growth

Add vs multiply

Which Function Type?

  1. Equal y differencesLinear(Constant rate)
  2. Constant y ratioExponential(Multiply)
  3. Equal 2nd differencesQuadratic(Parabola)
  4. Add same each stepArithmetic / linear(Common d)
  5. Multiply each stepGeometric / exponential(Common r)
  6. U-shaped graphQuadratic(Vertex)

Function Basics

f(x) notation
Output for input x
Domain
Allowed x inputs
Range
Possible y outputs
Function test
One y per x
Vertical line test
Graph crosses once
Avg rate of change
(f(b)-f(a))/(b-a)
x-intercept
Root, where y = 0
Discrete
Separate plotted points

Slope

Slope = rise over run

Rise = change in yRun = change in xUp-right positive

Domain vs Range

Domain

  • Inputs x
  • Read left-right
  • Allowed values

Range

  • Outputs y
  • Read bottom-up
  • Resulting values

x in vs y out

Exponential Models

General form
y = a * b^x
a value
Initial amount
b > 1
Growth factor
0 < b < 1
Decay factor
Growth rate r
b = 1 + r
Decay rate r
b = 1 - r
Constant ratio
Equal y multiples

Exponential

y = a times b to the x

a = startb > 1 growsb < 1 decays

Discrete vs Continuous

Discrete

  • Separate points
  • Countable items
  • No connecting

Continuous

  • Solid curve
  • Any value
  • Connected graph

Dots vs line

Sequences

Arithmetic
Add common difference d
Arithmetic nth
a_n = a_1 + (n-1)d
Geometric
Multiply common ratio r
Geometric nth
a_n = a_1 * r^(n-1)
Recursive
Uses previous term
Linear pattern
Arithmetic sequence
Exponential pattern
Geometric sequence

Transformations

f(x) + k
Shift up k
f(x) - k
Shift down k
f(x - h)
Shift right h
f(x + h)
Shift left h
-f(x)
Reflect over x-axis
a * f(x)
Vertical stretch a
f(-x)
Reflect over y-axis

Correlation vs Causation

Correlation

  • Move together
  • Measured by r
  • Pattern only

Causation

  • One causes other
  • Needs experiment
  • Not from r

Linked vs causes

Statistics

Mean
Sum / count
Median
Middle of ordered data
Correlation r
Range -1 to 1
r near 1
Strong positive linear
r near 0
Weak / no linear
Residual
Actual minus predicted
Good fit
Random residual scatter
Two-way table
Counts by categories

Mean vs Median

Mean

  • Average value
  • Sum / count
  • Shifted by outliers

Median

  • Middle value
  • Order first
  • Resists outliers

Average vs middle

Number + Quantity

Rational
Fraction of integers
Irrational
Non-repeating decimal
Rational +/- rational
Stays rational
Rational + irrational
Becomes irrational
Closure
Stays in same set
Units / accuracy
Match real context

Common Traps

Zero vs no solution

x = 0 is a value No solution means none

Slope vs intercept

m is the slope b is the y-intercept

Domain vs range

Domain is x inputs Range is y outputs

Add vs multiply exponents

Same base multiply: add Power of power: multiply

Vertex vs zeros

Vertex is turning point Zeros are x-intercepts

Correlation vs causation

r shows a pattern Pattern is not cause

Scale score vs percent

65 is scale score Not raw percent correct

Last Minute

  1. 1.Passing = scale score 65, not percent
  2. 2.35 questions, Parts I-IV, 3 hours
  3. 3.Graphing calculator and straightedge allowed
  4. 4.Reference sheet given at back
  5. 5.Quadratic: (-b +/- root b^2-4ac)/2a
  6. 6.Axis and vertex: x = -b/2a
  7. 7.Discriminant b^2-4ac: + two, 0 one
  8. 8.Slope m = (y2-y1)/(x2-x1)
  9. 9.Linear adds; exponential multiplies y = a*b^x
  10. 10.Define variable, write equation first
  11. 11.Show all work on constructed-response
  12. 12.Interpret slope, zeros, vertex in context
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