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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. a^0 =
The greatest value minus the smallest.
1
130pi
A subset.

2. (6sqrt3) x (2sqrt5) =
Yes - like radicals can be added/subtracted.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
III
An expression with just one term (-6x - 2a^2)

3. Volume for a cylinder?
C = 2(pi)r
Ax^2 + bx + c where a -b and c are constants and a /=0
Area of the base X height = (pi)hr^2
41 - 43 - 47

4. 5x^2 - 35x -55 = 0
A grouping of the members within a set based on a shared characteristic.
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
Its negative reciprocal. (-b/a)
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

5. Surface area for a cylinder?
2(pi)r^2 + 2(pi)rh
(a + b)^2
An infinite set.
37.5%

6. 5/6 in percent?
y = (x + 5)/2
x^(6-3) = x^3
83.333%
48

7. Factor a^2 + 2ab + b^2
5 OR -5
(a + b)^2
75:11
x^(2(4)) =x^8 = (x^4)^2

8. How to find the area of a sector?
Angle/360 x (pi)r^2
(amount of increase/original price) x 100%
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15

9. How to determine percent decrease?
(amount of decrease/original price) x 100%
All numbers multiples of 1.
10
Indeterminable.

10. What is the set of elements found in both A and B?
(base*height) / 2
0
A chord is a line segment joining two points on a circle.
The interesection of A and B.

11. What is the percent formula?
Two equal sides and two equal angles.
Part = Percent X Whole
71 - 73 - 79
18

12. Simplify the expression (p^2 - q^2)/ -5(q - p)
Triangles with same measure and same side lengths.
(p + q)/5
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
53 - 59

13. Can the output value of a function have more than one input value?
Yes. [i.e. f(x) = x^2 - 1
Divide by 100.
72
70

14. What is the sum of the angles of a triangle?
A 30-60-90 triangle.
The sum of digits is divisible by 9.
67 - 71 - 73
180 degrees

15. What is a subset?
Diameter(Pi)
A grouping of the members within a set based on a shared characteristic.
F(x + c)
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)

16. A brick with dimensions 10. 15 and 25 weighs 1.5 kg. A second brick (same density) has dimensions 12 - 18 - and 30. What is the weight of the second brick?
413.03 / 10^4 (move the decimal point 4 places to the left)
441000 = 1 10 10 10 21 * 21
The point of intersection of the systems.
2.592 kg

17. 25^(1/2) or sqrt. 25 =
The longest arc between points A and B on a circle'S diameter.
3
5 OR -5
C = (pi)d

18. What is the order of operations?
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
The set of input values for a function.
When the function is not defined for all real numbers -; only a subset of the real numbers.
From northeast - counterclockwise. I - II - III - IV

19. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
4:5
0
2.592 kg
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)

20. Length of an arc of a circle?
An expression with just one term (-6x - 2a^2)
Angle/360 x 2(pi)r
72
Even

21. What is a set with no members called?
10! / (10-3)! = 720
12! / 5!7! = 792
2sqrt6
The empty set - denoted by a circle with a diagonal through it.

22. a^2 - b^2 =
(a + b)^2
I
III
(a - b)(a + b)

23. What is the formula for compounded interest?
4a^2(b)
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.
500
1.7

24. What is a finite set?
x= (1.2)(.8)lw
(amount of increase/original price) x 100%
A set with a number of elements which can be counted.
A grouping of the members within a set based on a shared characteristic.

25. What is the 'Range' of a series of numbers?
The greatest value minus the smallest.
16.6666%
All numbers multiples of 1.
3

26. Convert 0.7% to a fraction.
7 / 1000
Infinite.
The union of A and B.
A central angle is an angle formed by 2 radii.

27. 4.809 X 10^7 =
.0004809 X 10^11
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
Diameter(Pi)
F(x + c)

28. The four angles around a point measure y - 2y - 35 and 55 respectively. What is the value of y?
90
A central angle is an angle formed by 2 radii.
2sqrt6
1

29. Find the surface area of a cylinder with radius 3 and height 12.
Its divisible by 2 and by 3.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
3 - -3
90pi

30. How to find the diagonal of a rectangular solid?
Diameter(Pi)
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
10
28. n = 8 - k = 2. n! / k!(n-k)!

31. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. How many different people can get the three prizes?
A chord is a line segment joining two points on a circle.
10! / 3!(10-3)! = 120
Angle/360 x 2(pi)r
A 30-60-90 triangle.

32. Which is greater? 200x^295 or 10x^294?
4.25 - 6 - 22
C = (pi)d
90pi
Relationship cannot be determined (what if x is negative?)

33. What is a central angle?
0
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
The longest arc between points A and B on a circle'S diameter.
A central angle is an angle formed by 2 radii.

34. 10^6 has how many zeroes?
3/2 - 5/3
61 - 67
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
6

35. What is the ratio of the surface area of a cube with an edge of 10 to the surface area of a rectangular solid with dimensions 2 - 4 - and 6?
The curve opens downward and the vertex is the maximum point on the graph.
71 - 73 - 79
75:11
1

36. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
N! / (n-k)!
Arc length = (n/360) x pi(2r) where n is the number of degrees.
A circle centered at -2 - -2 with radius 3.
53 - 59

37. To convert a percent to a fraction....
x^(2(4)) =x^8 = (x^4)^2
1/a^6
Divide by 100.
The set of output values for a function.

38. Circumference of a circle?
The curve opens downward and the vertex is the maximum point on the graph.
6
Diameter(Pi)
Sector area = (n/360) X (pi)r^2

39. Legs: 3 - 4. Hypotenuse?
...multiply by 100.
3 - -3
61 - 67
5

40. What are congruent triangles?
4a^2(b)
Triangles with same measure and same side lengths.
441000 = 1 10 10 10 21 * 21
(base*height) / 2

41. 0^0
x= (1.2)(.8)lw
Undefined
A circle centered at -2 - -2 with radius 3.
The overlapping sections.

42. A number is divisible by 6 if...
Its divisible by 2 and by 3.
70
C = (pi)d
F(x-c)

43. Formula to calculate arc length?
A = I (1 + rt)
Angle/360 x (pi)r^2
Arc length = (n/360) x pi(2r) where n is the number of degrees.
True

44. What are the members or elements of a set?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
5
The objects within a set.
A 30-60-90 triangle.

45. What is the coefficient of the x^2 term in the product of (x + 1)(x + 2)(x -1)?
2
6
Angle/360 x 2(pi)r
2 & 3/7

46. 1/8 in percent?
Its last two digits are divisible by 4.
True
12.5%
A chord is a line segment joining two points on a circle.

47. What is the graph of f(x) shifted downward c units or spaces?
90
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
F(x) - c
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. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
Diameter(Pi)
1
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
y = (x + 5)/2

49. What is the intersection of A and B?
An infinite set.
A set with no members - denoted by a circle with a diagonal through it.
N! / (n-k)!
The set of elements found in both A and B.

50. What is the side length of an equilateral triangle with altitude 6?
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...
3sqrt4
...multiply by 100.
87.5%