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# SAT Math Review

### review for some of the math sections on the SAT

Question | Answer |
---|---|

PERCENTS | Always plug in 100 for percent problems. |

AREA | Area of a triangle: 1/2base x heightArea of a square/rectangle: length x widthArea of a circle: pi x r2 |

DIAMETER | Square inside a circle, find diameter of circle: diagonal of square = length of side x square of 2. Radius = half of the diagonal of the square, diameter = diagonal of square. |

BACKSOLVING | simplify answers before looking at the problem. Start with answer C. |

EASY, MEDIUM, HARD | obvious answers in the "easy" section, at the beginning, are usually correct. Obvious answers in the "hard" section, at the end, are usually traps. |

GUESSING | Guess when you can eliminate at least one answer choice, like a trap answer on a hard question. You have much better odds that way. |

GRID INS | no negative answers. mixed answers must be converted to an improper fraction or a decimal. Start gridding in the first column, grid answer of 0 in other columns. No negatives, variables, or more than 4 digits. |

DECIMAL ACCURACY | if the answer is .1666666, record as .166 or .167. |

ORDER OF OPERATIONS | PEMDAS. Please Excuse My Dear Aunt Sally. Parentheses, Exponents, Multiplication, Division, Addition, Subtraction. |

SETS | A set is made up of elements (numbers). Set K = 1, 3, 5, 7, 8. Elements are 1, 3, 5, 7, 8. Union of sets: putting together the sets. Set P = 2, 3, 4, 5. k U p = 1, 2, 3, 4, 5, 7, 8. Intersection of sets: Elements that are common. K n P = 3, 5 |

DIVISIBILITY | - 2 last digit can be divided by 2- 3 sum of digits is a multiple of 3- 4 last two digits are a multiple of 4- 5 last digit is 0 or 5- 6 last digit is 2 or 3- 9 sum of digits is a multiple of 9 |

EXPONENTIAL GROWTH | Geometric Sequences. 4, 18, 16, 32, 64, 128, 256. Ratio between terms = 2 ^ Each term = the previous term x 2. Formula = An=A1R^n-1 (r = 2, a1 = 4. a10 = 4(2^9) The tenth in the sequence = 2048.) |

ABSOLUTE VALUE | distance of the number from 0 on the numberline. Always positive. Absolute value of 7 = 7. Every positive number is the absoulte value of itself and it's negative. Expressed |7| = 7 |

DOMAIN | domain is a set of values for which a function is defined. f(x)=1/1-x^2 is all the values of x except 1 and -1 |

RANGE | set of all results for a function. Range of f(x)=x^2 is all numbers greater than or equal to 0, because x^2 cannot be negative. |

DIRECT VARIATION | y = kx. If the x variable changes, the y variable does as well. The k value is constant. |

AVERAGE | Sum of average = average x number of terms. Total sum/total number of terms = average of two groups. |

MODE | the number that appears most frequently in a group of numbers. |

MEDIAN | number in the middle of a line of numbers. With an even number of terms, median = the average between the two middle terms. |

RATE | Distance = rate x time |

INCREASE/DECREASE | Increase/decrease = increase-decrease/original whole x 100%. Subtract original whole from the new whole. |