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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 |