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GRE
Study
Question | Answer |
---|---|
In FRACTIONS with the SAME NUMERATOR... | the smaller denominator is the larger fraction |
in FRACTIONS with the SAME DENOMINATOR... | the larger numerator is the larger fraction |
to solve for larger fractions with unlike parts... | cross multiply keeping numerators of the same side OR find a common numerator or denominator |
Positive# * Positive Fraction = | a smaller # |
Negative# * Positve Fraction= | a larger # |
# is divisible by 2 if... | the number is even |
# is divisible by 3 if... | the sum of its digits are divisible by 3 |
# is divisible by 4 if... | the last two digits are divisible by 4 |
# is divisible by 5 if... | it ends in 5 or 0 |
# is divisible by 6 if... | it is divisible by 2 and 3 |
# is divisible by 9 if... | the sum of its digits are divisible by 9 |
The PROBABILITY of an event = | (# of desired outcomes)/ (# of possible outcomes) |
MULTI-STEP PROBABILITY problem= | (Prob of E#1)*(Prob of E#2) |
When MULTIPLYING same numbers with different powers... | add the exponents |
When DIVIDING same numbers with different powers... | subtract the exponents |
When you have a number with a power raised to a power... | multiply the exponents |
A number to the power "0" = | 1 (except if the number is "0") |
A number to a NEGATIVE POWER = | 1 / (number to positive power) |
A number to a FRACTION POWER = | a ROOT |
3 steps to solve an ALGEBRAIC INEQUALITY: | 1) multiply to get rid of fractions 2) isolate "x" by adding or subtracting to each side 3) multiply by -1 to get positive "x" which will change direction of inequality ( < to >) |
6 steps to solve for VARIABLE IN TERMS OF ANOTHER: | isolate variable alone on one side*1) cross-multiplying 2) remove () by distributing 3) move terms w/ variable to one side 4) factor out the variable 5) divide to get the variable alone 6) if necessary multiply by -1 to get rid of negative terms |
3 steps to solve QUADRATIC EQUATION: | *always has TWO answers* 1) set it equal to "0" 2) factor it out 3) find values that make each factor equal to "0" |
"pi" is approximately equal to ... | 3.14 |
square root of 2 is approximately equal to... | 1.4 |
the square root of 3 is approximately equal to... | 1.7 |
sum of angles of a straight line = | 180 |
sum of angles around a point = | 360 |
SUPPLEMENTARY angles | make a straight line and =180 |
COMPLIMENTARY angles | make a right angle and = 90 |
To get the slope from 2 points | (change in Y) / (change in X) |
To get slope from an equation | put it into "y = mx + b" format |
the sum of the interior angles of a triangle = | 180 |
the length of any side of a triangle is... | less than the sum of the other 2 sides AND greater than the difference of the other 2 sides |
The greatest angle in a traingle... | lies opposite the longest side |
Triangle Area = | (1/2)base * height |
ISOSCELES triangles... | have two sides of equal length ( and therefore two equal angles) |
EQUILATERAL triangle... | has three sides of equal length and three equal angles |
the ratio of the area of similar triangles... | is the square of the ratio of their sides |
3 traingles that fit neatly in the PYTHAGOREAN theorem are... | (3, 4, 5) (6, 8, 10) and (5, 12, 13) |
ratio of sides in a 45-45-90 right triangle are | 1:1: √2 |
ratio of sides in a 30-60-90 triangle is | 1: √3:2 |
sum of interior angles of a POLYGON = | (#sides-2) *180 |
sum of interior angles of a QUADRILATERAL = | 360 |
CIRCUMFERENCE of a CIRCLE = | C = 2πr OR πd |
AREA of a CIRCLE | A = π(r)squared |
Finding ARC length | ARC/Circumference = central angle / 360 |
CHORD | a straight line connecting two points on a circle... can never be longer than the diameter |
VOLUME of a RECTANGULAR SOLID = | length*width*height |
SURFACE AREA of a RECTANGULAR SOLID = | sum of area of faces = 2lw + 2lh + 2wh |
VOLUME of a CYLINDER = | area of base * height = π(r)sq * h |
LATERAL SURFACE AREA of a CYLINDER = | circumference of base * height |
t | h |