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GRE Math: Common Errors

Subjects : gre, 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. Evaluate 3& 2/7 / 1/3
87.5%
12! / 5!7! = 792
9 & 6/7
1

2. Factor a^2 + 2ab + b^2
(a + b)^2
(amount of increase/original price) x 100%
F(x) - c
Yes - like radicals can be added/subtracted.

3. Factor x^2 - xy + x.
x(x - y + 1)
Its last two digits are divisible by 4.
2^9 / 2 = 256
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

4. 5 bakeries sell an average of 300 muffins per bakery per day. If 2 stop making muffins but the total muffins sold stays the same - what is the average of muffins per bakery sold among the remaining?
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
500
16.6666%
Two angles whose sum is 180.

5. What are the rational numbers?
1
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
4725
1

6. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
12.5%
10
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
27^(-4)

7. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
0
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
$3 -500 in the 9% and $2 -500 in the 7%.
67 - 71 - 73

8. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
90
12! / 5!7! = 792
7 / 1000
Sqrt 12

9. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
$11 -448
Members or elements
180
A chord is a line segment joining two points on a circle.

10. How to determine percent decrease?
11 - 13 - 17 - 19
An algebraic expression is a combination of one of more terms. Terms in an expression are separated by either addition or subtraction signs. (3xy - 4ab - -5cd - x^2 + x - 1)
The objects within a set.
(amount of decrease/original price) x 100%

11. If the two sides of a triangle are unequal then the longer side...
A central angle is an angle formed by 2 radii.
Lies opposite the greater angle
10! / 3!(10-3)! = 120
G(x) = {x}

12. When the 'a' in a parabola is positive....
48
The curve opens upward and the vertex is the minimal point on the graph.
4725
y = (x + 5)/2

13. What is the 'Range' of a series of numbers?
130pi
The greatest value minus the smallest.
No - only like radicals can be added.
Area of the base X height = (pi)hr^2

14. If a=-1 and b=3 - what is the value of (4(a^3)(b^2) - 12(a^2)(b^5)) / (16(a^3)(b^2))?
18
20.5
Ax^2 + bx + c where a -b and c are constants and a /=0
No - only like radicals can be added.

15. (12sqrt15) / (2sqrt5) =
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
413.03 / 10^4 (move the decimal point 4 places to the left)
A= I (1 + (r/c))^tC - where I is the investment - C is the number of times compounded annually - and t is the number of years.
0

16. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
48
Yes - like radicals can be added/subtracted.
13pi / 2

17. (-1)^2 =
62.5%
1
37.5%
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)

18. Define an 'expression'.
4.25 - 6 - 22
An algebraic expression is a combination of one of more terms. Terms in an expression are separated by either addition or subtraction signs. (3xy - 4ab - -5cd - x^2 + x - 1)
The direction of the inequality is reversed.
Triangles with same measure and same side lengths.

19. What is the sum of the angles of a triangle?
Members or elements
180 degrees
No - only like radicals can be added.
4725

20. What is a tangent?
31 - 37
An arc is a portion of a circumference of a circle.
A tangent is a line that only touches one point on the circumference of a circle.
62.5%

21. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
4725
(amount of decrease/original price) x 100%
(p + q)/5
1/2 times 7/3

22. Max and Min lengths for a side of a triangle?
The third side is greater than the difference and less than the sum.
A set with a number of elements which can be counted.
61 - 67
(p + q)/5

23. How to find the diagonal of a rectangular solid?
13
Cd
500
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

24. a^2 + 2ab + b^2
(a + b)^2
All the numbers on the number line (negative - rational - irrational - decimal - integer). All the numbers on the GRE are real. (-2 - 1 - .25 - 1/2 - pi)
y = 2x^2 - 3
A= I (1 + (r/c))^tC - where I is the investment - C is the number of times compounded annually - and t is the number of years.

25. Formula of rectangle where l increases by 20% and w decreases by 20%
x= (1.2)(.8)lw
Indeterminable.
Sector area = (n/360) X (pi)r^2
2^9 / 2 = 256

26. A number is divisible by 3 if ...
The empty set - denoted by a circle with a diagonal through it.
3/2 - 5/3
The sum of its digits is divisible by 3.
...multiply by 100.

27. What is a parabola?
87.5%
Sqrt 12
Ax^2 + bx + c where a -b and c are constants and a /=0
2.4. We calculate the area (6) and then turn the triangle on its side and use x as the height to calculate again. (5x)/2=6

28. Volume for a cylinder?
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
Area of the base X height = (pi)hr^2
The second graph is less steep.
The greatest value minus the smallest.

29. When does a function automatically have a restricted domain (2)?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
31 - 37
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
72

30. What is the order of operations?
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
Its divisible by 2 and by 3.
(a - b)(a + b)
A chord is a line segment joining two points on a circle.

31. Can you simplify sqrt72?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
288 (8 9 4)
A circle centered on the origin with radius 8.
A circle centered at -2 - -2 with radius 3.

32. A number is divisible by 6 if...
Its divisible by 2 and by 3.
41 - 43 - 47
3
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

33. How many sides does a hexagon have?
18
1:sqrt3:2
4sqrt3. The triangle can be divided into two equal 30-60-90 triangles with side 6 as the side in which 6 = xsqrt3. So x =2sqrt3...
6

34. Which quadrant is the lower left hand?
III
F(x + c)
52
(base*height) / 2

35. If an inequality is multiplied or divided by a negative number....
72
A subset.
A chord is a line segment joining two points on a circle.
The direction of the inequality is reversed.

36. Write 10 -843 X 10^7 in scientific notation
1.0843 X 10^11
The sum of its digits is divisible by 3.
The set of input values for a function.
10! / 3!(10-3)! = 120

37. Evaluate 4/11 + 11/12
1 & 37/132
(a - b)(a + b)
(a - b)(a + b)
(12/2) x (sqrt15 / sqrt5) = 6sqrt3

38. If you have a set of n objects - but you only want to order k of them - what formula do you use to determine the number of permutations?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
Divide by 100.
$11 -448
N! / (n-k)!

39. What is the 'domain' of a function?
The set of input values for a function.
The second graph is less steep.
The point of intersection of the systems.
1.7

40. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
130pi
An expression with just one term (-6x - 2a^2)
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Part = Percent X Whole

41. x^(-y)=
90 degrees
1/(x^y)
72
A tangent is a line that only touches one point on the circumference of a circle.

42. Suppose that the graph of f(x) is the result of sliding the graph of y=2x^2 down 3 units of spaces. What is the new equation?
The interesection of A and B.
y = 2x^2 - 3
The set of elements which can be found in either A or B.
The point of intersection of the systems.

43. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
A reflection about the axis.
12! / 5!7! = 792
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
The union of A and B.

44. 50 < all primes< 60
x^(4+7) = x^11
53 - 59
180 degrees
2sqrt6

45. What is an exterior angle?
2(pi)r^2 + 2(pi)rh
1.0843 X 10^11
An angle which is supplementary to an interior angle.
Undefined - because we can'T divide by 0.

46. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
The third side is greater than the difference and less than the sum.
13pi / 2
9 : 25
8

47. What are the roots of the quadrinomial x^2 + 2x + 1?
The two xes after factoring.
Two angles whose sum is 90.
4096
A term is a numerical constant or the product (or quotient) of a numerical constant and one or more variables. (3x - 4x^2 and 2a/c)

48. Circumference of a circle?
13
No - only like radicals can be added.
Diameter(Pi)
(n-2) x 180

49. What are the members or elements of a set?
Diameter(Pi)
Yes - like radicals can be added/subtracted.
True
The objects within a set.

50. How many multiples does a given number have?
The third side is greater than the difference and less than the sum.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
An angle which is supplementary to an interior angle.
Infinite.