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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. 6w^2 - w - 15 = 0
Yes - like radicals can be added/subtracted.
53 - 59
12sqrt2
3/2 - 5/3

2. When the 'a' in a parabola is positive....
4a^2(b)
2sqrt6
The curve opens upward and the vertex is the minimal point on the graph.
Area of the base X height = (pi)hr^2

3. Legs: 3 - 4. Hypotenuse?
5
441000 = 1 10 10 10 21 * 21
1.0843 X 10^11
(b + c)

4. Reduce: 4.8 : 0.8 : 1.6
Two equal sides and two equal angles.
6 : 1 : 2
6
2 & 3/7

5. Evaluate 3& 2/7 / 1/3
A reflection about the axis.
Arc length = (n/360) x pi(2r) where n is the number of degrees.
9 & 6/7
The curve opens downward and the vertex is the maximum point on the graph.

6. What are the rational numbers?
Divide by 100.
Angle/360 x (pi)r^2
4725
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)

7. Legs 5 - 12. Hypotenuse?
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)
Infinite.
13
87.5%

8. What are the smallest three prime numbers greater than 65?
67 - 71 - 73
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
18
Move the decimal point to the right x places

9. What is the ratio of the sides of an isosceles right triangle?
Cd
1:1:sqrt2
Angle/360 x 2(pi)r
The sum of its digits is divisible by 3.

10. What are the integers?
The curve opens downward and the vertex is the maximum point on the graph.
0
90 degrees
All numbers multiples of 1.

11. What is the 'Restricted domain of a function'?
A 30-60-90 triangle.
1
Part = Percent X Whole
When the function is not defined for all real numbers -; only a subset of the real numbers.

12. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
70
F(x) + c
The union of A and B.
1

13. What are congruent triangles?
N! / (k!)(n-k)!
Pi is the ratio of a circle'S circumference to its diameter.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Triangles with same measure and same side lengths.

14. What percent of 40 is 22?
1
7 / 1000
72
55%

15. How to determine percent decrease?
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
9 & 6/7
(amount of decrease/original price) x 100%
An infinite set.

16. Which quadrant is the upper right hand?
Members or elements
I
12sqrt2
1/2 times 7/3

17. Can you simplify sqrt72?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
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)
I
72

18. 25^(1/2) or sqrt. 25 =
16.6666%
No - only like radicals can be added.
5 OR -5
1.7

19. What is the graph of f(x) shifted upward c units or spaces?
F(x) + c
11 - 13 - 17 - 19
The set of elements which can be found in either A or B.
90 degrees

20. x^4 + x^7 =
x^(4+7) = x^11
Members or elements
4a^2(b)
Undefined

21. The number of degrees in the largest angle of a triangle inscribed in a circle - in which the diameter of the circle is one side of the triangle.
C = 2(pi)r
90 degrees
61 - 67
The direction of the inequality is reversed.

22. What are complementary angles?
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.
Two angles whose sum is 90.
20.5
13

23. How many multiples does a given number have?
Diameter(Pi)
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Infinite.
180 degrees

24. Convert 0.7% to a fraction.
7 / 1000
...multiply by 100.
8
6

25. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
Triangles with same measure and same side lengths.
$11 -448
9 & 6/7
Sector area = (n/360) X (pi)r^2

26. 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?
A set with a number of elements which can be counted.
N! / (n-k)!
x^(2(4)) =x^8 = (x^4)^2
Relationship cannot be determined (what if x is negative?)

27. What is the 'Range' of a function?
1 & 37/132
Angle/360 x (pi)r^2
IV
The set of output values for a function.

28. Define an 'expression'.
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
180 degrees
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
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)

29. A cylinder has a surface area of 22pi. If the cylinder has a height of 10 - what is the radius?
11 - 13 - 17 - 19
4a^2(b)
1
2.592 kg

30. Factor x^2 - xy + x.
x(x - y + 1)
A chord is a line segment joining two points on a circle.
Sqrt 12
True

31. 10<all primes<20
11 - 13 - 17 - 19
4725
67 - 71 - 73
(a - b)(a + b)

32. x^6 / x^3
1
x= (1.2)(.8)lw
x^(6-3) = x^3
The curve opens upward and the vertex is the minimal point on the graph.

33. Simplify the expression [(b^2 - c^2) / (b - c)]
12.5%
61 - 67
(b + c)
The set of elements which can be found in either A or B.

34. What is a finite set?
A set with a number of elements which can be counted.
(amount of increase/original price) x 100%
Relationship cannot be determined (what if x is negative?)
75:11

35. What is the graph of f(x) shifted right c units or spaces?
An infinite set.
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
F(x-c)
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

36. Surface area for a cylinder?
2(pi)r^2 + 2(pi)rh
An isosceles right triangle.
Arc length = (n/360) x pi(2r) where n is the number of degrees.
10! / 3!(10-3)! = 120

37. The objects in a set are called two names:
Members or elements
2.592 kg
67 - 71 - 73
A tangent is a line that only touches one point on the circumference of a circle.

38. What does scientific notation mean?
8
The direction of the inequality is reversed.
27^(-4)
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

39. What is the 'domain' of a function?
.0004809 X 10^11
1.0843 X 10^11
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
The set of input values for a function.

40. What is the ratio of the sides of a 30-60-90 triangle?
1:sqrt3:2
When the function is not defined for all real numbers -; only a subset of the real numbers.
3
The sum of digits is divisible by 9.

41. 50 < all primes< 60
2 & 3/7
53 - 59
441000 = 1 10 10 10 21 * 21
4:5

42. 5x^2 - 35x -55 = 0
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
1/2 times 7/3
$11 -448
(amount of increase/original price) x 100%

43. Formula to find a circle'S circumference from its radius?
C = 2(pi)r
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
A reflection about the axis.
(b + c)

44. (12sqrt15) / (2sqrt5) =
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
10
A tangent is a line that only touches one point on the circumference of a circle.

45. Which is greater? 200x^295 or 10x^294?
The steeper the slope.
5 OR -5
(p + q)/5
Relationship cannot be determined (what if x is negative?)

46. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
x= (1.2)(.8)lw
The longest arc between points A and B on a circle'S diameter.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
13pi / 2

47. Formula to find a circle'S circumference from its diameter?
Its negative reciprocal. (-b/a)
C = (pi)d
(a - b)(a + b)
52

48. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
A subset.
The set of elements found in both A and B.
1
Relationship cannot be determined (what if x is negative?)

49. Length of an arc of a circle?
Indeterminable.
4.25 - 6 - 22
Angle/360 x 2(pi)r
A 30-60-90 triangle.

50. Which quadrant is the upper left hand?
Undefined - because we can'T divide by 0.
A reflection about the axis.
II
N! / (n-k)!