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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. Factor a^2 + 2ab + b^2
The greatest value minus the smallest.
(n-2) x 180
(a + b)^2
The union of A and B.

2. What is the area of a regular hexagon with side 6?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
Members or elements
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.

3. What number between 70 & 75 - inclusive - has the greatest number of factors?
Even
72
48
Undefined

4. 3/8 in percent?
37.5%
1
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
67 - 71 - 73

5. What is a parabola?
...multiply by 100.
1:1:sqrt2
Its last two digits are divisible by 4.
Ax^2 + bx + c where a -b and c are constants and a /=0

6. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. In how many ways can the judges award the 3 prizes?
10! / (10-3)! = 720
F(x) - c
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
52

7. 2sqrt4 + sqrt4 =
3sqrt4
A circle centered on the origin with radius 8.
20.5
3 - -3

8. A number is divisible by 6 if...
Its divisible by 2 and by 3.
130pi
(amount of decrease/original price) x 100%
...multiply by 100.

9. Which quadrant is the upper right hand?
11 - 13 - 17 - 19
5 OR -5
2^9 / 2 = 256
I

10. 10^6 has how many zeroes?
90 degrees
1
6
16.6666%

11. Convert 0.7% to a fraction.
7 / 1000
A set with no members - denoted by a circle with a diagonal through it.
Relationship cannot be determined (what if x is negative?)
1.7

12. Formula to find a circle'S circumference from its diameter?
(a + b)^2
C = (pi)d
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
23 - 29

13. What is an exterior angle?
An angle which is supplementary to an interior angle.
1.0843 X 10^11
2^9 / 2 = 256
The third side is greater than the difference and less than the sum.

14. What is the set of elements which can be found in either A or B?
6
The union of A and B.
The sum of digits is divisible by 9.
12sqrt2

15. Write 10 -843 X 10^7 in scientific notation
1
6
1.0843 X 10^11
12sqrt2

16. To multiply a number by 10^x
Factors are few - multiples are many.
When the function is not defined for all real numbers -; only a subset of the real numbers.
4.25 - 6 - 22
Move the decimal point to the right x places

17. Find the surface area of a cylinder with radius 3 and height 12.
67 - 71 - 73
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
G(x) = {x}
90pi

18. Can you add sqrt 3 and sqrt 5?
1
(b + c)
Ax^2 + bx + c where a -b and c are constants and a /=0
No - only like radicals can be added.

19. To convert a decimal to a percent...
...multiply by 100.
Arc length = (n/360) x pi(2r) where n is the number of degrees.
F(x) + c
(p + q)/5

20. Volume for a cylinder?
F(x-c)
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
1/a^6
Area of the base X height = (pi)hr^2

21. If the 80th percentile of the measurements is 72degrees - about how many measurments are between 69 degrees and 72 degrees? Round your answer to the nearest tenth
Members or elements
An arc is a portion of a circumference of a circle.
18
500

22. What is the graph of f(x) shifted downward c units or spaces?
Its last two digits are divisible by 4.
1.0843 X 10^11
9 & 6/7
F(x) - c

23. Define a 'monomial'
87.5%
28. n = 8 - k = 2. n! / k!(n-k)!
An expression with just one term (-6x - 2a^2)
1

24. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
Cd
The direction of the inequality is reversed.
Diameter(Pi)
An arc is a portion of a circumference of a circle.

25. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
3
4a^2(b)
4:5
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)

26. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
Two angles whose sum is 90.
A reflection about the axis.
16.6666%
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

27. What is the graph of f(x) shifted right c units or spaces?
41 - 43 - 47
F(x-c)
Undefined - because we can'T divide by 0.
4.25 - 6 - 22

28. What does scientific notation mean?
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
3sqrt4
Factors are few - multiples are many.

29. How many 3-digit positive integers are even and do not contain the digit 4?
288 (8 9 4)
C = 2(pi)r
55%
The longest arc between points A and B on a circle'S diameter.

30. Simplify the expression [(b^2 - c^2) / (b - c)]
All numbers multiples of 1.
(b + c)
48
1 & 37/132

31. How to find the circumference of a circle which circumscribes a square?
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
13pi / 2
A circle centered on the origin with radius 8.
12.5%

32. Length of an arc of a circle?
Angle/360 x 2(pi)r
A set with a number of elements which can be counted.
Yes. [i.e. f(x) = x^2 - 1
Sector area = (n/360) X (pi)r^2

33. Order of quadrants:
Divide by 100.
23 - 29
From northeast - counterclockwise. I - II - III - IV
4:5

34. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
IV
A chord is a line segment joining two points on a circle.
C = (pi)d
4725

35. What is the ratio of the sides of a 30-60-90 triangle?
Angle/360 x 2(pi)r
1:sqrt3:2
y = 2x^2 - 3
13pi / 2

36. 5/6 in percent?
90 degrees
Its last two digits are divisible by 4.
Lies opposite the greater angle
83.333%

37. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
F(x-c)
...multiply by 100.
1
y = 2x^2 - 3

38. Evaluate 3& 2/7 / 1/3
(a - b)^2
87.5%
9 & 6/7
F(x + c)

39. 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 third side is greater than the difference and less than the sum.
IV
N! / (n-k)!
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.

40. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
13pi / 2
28. n = 8 - k = 2. n! / k!(n-k)!
The interesection of A and B.
Two equal sides and two equal angles.

41. Is 0 even or odd?
12sqrt2
8
Even
Ax^2 + bx + c where a -b and c are constants and a /=0

42. a^2 + 2ab + b^2
(a + b)^2
(a - b)(a + b)
(amount of decrease/original price) x 100%
The interesection of A and B.

43. (x^2)^4
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
x^(2(4)) =x^8 = (x^4)^2
53 - 59
No - the input value has exactly one output.

44. P and r are factors of 100. What is greater - pr or 100?
The interesection of A and B.
Indeterminable.
87.5%
41 - 43 - 47

45. If the two sides of a triangle are unequal then the longer side...
IV
A reflection about the axis.
Lies opposite the greater angle
75:11

46. What is a minor arc?

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47. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
Its divisible by 2 and by 3.
A set with no members - denoted by a circle with a diagonal through it.
Lies opposite the greater angle
A 30-60-90 triangle.

48. 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.
90 degrees
F(x + c)
The two xes after factoring.
3/2 - 5/3

49. Evaluate (4^3)^2
67 - 71 - 73
IV
90
4096

50. 1/6 in percent?
2.592 kg
37.5%
16.6666%
27^(-4)