# SAT Math: Concepts And Tricks

Subjects : sat, math
Instructions:
• Answer 50 questions in 15 minutes.
• If you are not ready to take this test, you can study here.
• Match each statement with the correct term.
• Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. To multiply or divide integers - firstly ignore the sign and compute the problem - given 2 negatives make a positive - 2 positives make a positive - and one negative - and one positive make a negative attach the correct sign

2. To find the prime factorization of an integer just keep breaking it up into factors until all the factors are prime

3. To find the y-intercept: put the equation into slope-intercept form (b is the y-intercept): y=mx+b or plug x=0 and solve for y - To find the x-intercept: plug y=0 and solve for x

4. Multiply te coefficients and the variables separately Example: 2a*3a Work: (23)(aa) Answer: 6a^2

5. The length of one side of a triangle must be greater than the difference and less than the sum of the lengths of the other two sides

6. To divide fractions - invert the second one and multiply

7. This is the key to solving most fraction and percent word problems. Part is usually associated with the word is/are and whole is associated with the word of. Example: 'half of the boys are blonds' whole: all of the boys part: blonds

8. Average A per B: (total A)/(total B) - Example: average speed formula - total distance/ total time - Basically: Don't just average the 2 speeds

9. Part = Percent x Whole

10. To multiply fractions - multiply the numerators and multiply the denominators

11. Volume of a Cylinder = pr^2h

12. Integers are whole numbers; they include negtavie whole numbers and zero - Rational numbers can be expressed as a ratio of two integers - irration numbers are real numbers that cant be expressed precisely as a fraction or decimal.

13. A sector is a piece of the area of a circle. If n is the degree measure of the sector's central angle then the formula is: Area of a Sector = (n/360) (pr^2)

14. To reduce a fraction to lowest terms - factor out and cancel all factors the numerator and denominator have in common

15. Expressed A?B (' A union B ') - is the set of all members contained in either A or B or both.

16. An arc is a piece of the circumference. If n is the degree measure of the arc's central angle - then the formula is: Length of an Arc = 1 (n/360) (2pr)

17. If a right triangle's leg-to-leg ratio is 5:12 - or if the leg-to-hypotenuse ratio is 5:13 or 12:13 - it's a 5-12-13 triangle

18. Start with 100 as a starting value - Example: A price rises by 10% one year and by 20% the next. What's the combined percent increase? - Say the original price is \$100. Year one: \$100 + (10% of 100) = 100 + 10 = 110 Year two: 110 + (20% of 110) = 110

19. Combine equations in such a way that one of the variables cancel out

20. To solve an inequality do whatever is necessary to both sides to isolate the variable. When you multiply or divide both sides by a negative number you must reverse the sign

21. Use this example: Example: after a 5% increase - the population was 59 -346. What was the population before the increase? Work: 1.05x=59 -346 Answer: 56 -520

22. The absolute value of a number is the distance of the number from zero - since absolute value is distance it is always positive

23. Surface Area = 2lw + 2wh + 2lh

24. Divisible by 2 if: last digit is even - divisible by 4 if: last two digits form a multiple of 4

25. Factor can be divisible (factor of 12 and 8 is 4). Multiple is a multiple (multiple of 12 and 8 is 24).

26. 1. turn it into ax^2 + bx + c = 0 form 2. factor 3. set both factors equal to zero 4. you get 2 solutions

27. Multiplying: multiply the #s inside the root - but KEEP the ROOT sign - dividing: divide the #s inside the root - but KEEP the ROOT sign

28. To solve a proportion - cross multiply

29. Add up numbers and divide by the number of numbers - Average=(sum of terms)/(# of terms)

30. Area of Triangle = 1/2 (base)(height) - the height is the perpendicular distance between the side that's chosen as the base and the opposite vertex

31. To evaluate an algebraic expression - plug in the given values for the unknowns and calculate according to PEMDAS

32. To increase: add decimal version of percent to one and times that # to the # you want to increase. Example: increase 40 by 25% Work: 1.25*40=? Answer: 50

33. When two lines intersect - adjacent angles (angles next to each other) are supplementary (=180) and vertical angles are equal

34. Combine like terms

35. 1. Re-express them with common denominators 2. Convert them to decimals

36. An isosceles triangle has 2 equal sides and the angles opposite the equal sides (base angles) are also equal - an equaliteral is a triangle where all 3 sides are equal - thus the angles are equal - regardless of side length the angle is always 60 deg

37. Growth pattern in which the individuals in a population reproduce at a constant rate; j-curve graph-- logarithmic - FORMULA: y=a(1+r)^ EXPLANATION: a = initial amount before measuring growth/decay r = growth/decay rate (often a percent) x = number of

38. Probability= Favorable Outcomes/Total Possible Outcomes

39. The 3 angles of any triangle add up to 180 degrees - an exterior angles of a triangle is equal to the sum of the remote interior angles - the 3 exterior angles add up to 360 degrees

40. Notation: f(x) read: 'f of x' evaluation: if you want to evaluate the function for f(4) - replace x with 4 everywhere in the equation

41. Direct variation: equation: y=kx - where k is a nonzero constant trick: y changes directly as x does inverse variation: equation: xy=k trick: y doubles as x halves and vice-versa

42. The whole # left over after division

43. Integers that have no common factor other than 1 - to determine whether two integers are relative primes break them both down to their prime factorizations

44. A decimal with a sequence of digits that repeats itself indefinitely; to find a particular digit in the repetition - use the example: if there are 3 digits that repeat - every 3rd digit is the same. If you want the 31st digit - then the 30th digit is

45. To find the reciprocal of a fraction switch the numerator and the denominator

46. The sum of the measures of the interior angles of a polygon = (n - 2) 180 - where n is the number of sides

47. All acute angles are = all obtuse angles are = any obtuse angle+any acute angle= 180

48. The largest factor that two or more numbers have in common.

49. # associated with of on top - # associated with to on bottom Example: ratio of 20 oranges to 12 apples? Work: 20/12 Answer: 5/3

50. A square is a rectangle with four equal sides; Area of Square = side*side