GRE Math Formulas and Definitions
Terms
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- LCD
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1. Write prime factors out
2. Cross out any PF in second denom. that appears in first denom
3. Multiply remaining factors -
Averages:
Mean
Median
Mode -
Mean: Sum of #s/ # of elements
Median: Middle
Mode: Most often - Average of X #s = Y...
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X = number of elements
Y = the average
Therefore, if sum/X = Y
Sum = XY - Ratio/Proportion
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Ratio- compares 2 #s
Proportion- two equal ratios -
(-X)^2,4,6,8,10...
(-X)^1,3,5,9... -
Even power- Always positive
Odd power- Always negative - Binomial Squares
- FOIL- First, Outer, Inner, Last
- Linear Equation
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-Highest power of any variable is 1
-Solve by isolating variable on 1 side - Quadratic Equation
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-At least one variable is raised to 2nd power
-Set one side of equation = 0
-Factor out non-zero side
-Set each Factor = 0 and solve - Area of Triangle
- A = 1/2bh
- Rectangle Area, Perimeter
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A = lw
P = 2l + 2w - Circle
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A = Pi r^2
C = Pi d or 2Pi r - Length of Arc
- Arc AB = (X/360) x 2Pi r
- Pi
- 3.14 or 22/7
- Inscribed Angle
- 1/2 measure of intercepted Arc
- Surface Area of a Cube
- S = 6a^2
- Volume, SA
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V = lwh
SA = sum of areas of all faces - Distance
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d =
Radical( x1-x2)^2 + (y1-y2)^2 - Midpoint
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MP =
__x1+x2__ , __y1+y2__
2 2 - Slope
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__y1-y2__
x1-x2
if (x1 does NOT = x2) - Fraction Denominatiors
- Denominator decreases as Value increases
- Algebraic expressions
- Factor, Rearrange, Multiply Out