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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. What is the ratio of the sides of an isosceles right triangle?
1:1:sqrt2
4725
(a + b)^2
62.5%

2. x^4 + x^7 =
6
62.5%
x^(4+7) = x^11
Divide by 100.

3. a^2 + 2ab + b^2
3/2 - 5/3
1
(a + b)^2
28. n = 8 - k = 2. n! / k!(n-k)!

4. Convert 0.7% to a fraction.
y = (x + 5)/2
The longest arc between points A and B on a circle'S diameter.
7 / 1000
28. n = 8 - k = 2. n! / k!(n-k)!

5. What is the sum of the angles of a triangle?
4a^2(b)
180 degrees
90 degrees
III

6. Which is greater? 27^(-4) or 9^(-8)
2.592 kg
Triangles with same measure and same side lengths.
48
27^(-4)

7. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
Cd
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
No - only like radicals can be added.
28. n = 8 - k = 2. n! / k!(n-k)!

8. 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
4725
$3 -500 in the 9% and $2 -500 in the 7%.
Yes - like radicals can be added/subtracted.

9. Circumference of a circle?
Diameter(Pi)
x^(2(4)) =x^8 = (x^4)^2
The interesection of A and B.
72

10. What is the side length of an equilateral triangle with altitude 6?
500
72
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)
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...

11. What is the 'Restricted domain of a function'?
23 - 29
(a + b)^2
When the function is not defined for all real numbers -; only a subset of the real numbers.
The set of output values for a function.

12. 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.
(n-2) x 180
90 degrees
10! / 3!(10-3)! = 120
2^9 / 2 = 256

13. 50 < all primes< 60
4725
53 - 59
10! / 3!(10-3)! = 120
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16

14. What is a central angle?
The curve opens downward and the vertex is the maximum point on the graph.
1
180
A central angle is an angle formed by 2 radii.

15. The slope of a line perpendicular to (a/b)?
The longest arc between points A and B on a circle'S diameter.
28. n = 8 - k = 2. n! / k!(n-k)!
Its negative reciprocal. (-b/a)
A = I (1 + rt)

16. If an inequality is multiplied or divided by a negative number....
All numbers multiples of 1.
2
2(pi)r^2 + 2(pi)rh
The direction of the inequality is reversed.

17. 6w^2 - w - 15 = 0
13
37.5%
3/2 - 5/3
52

18. Simplify the expression (p^2 - q^2)/ -5(q - p)
13pi / 2
Sqrt 12
(p + q)/5
12sqrt2

19. What is the 'Solution' for a system of linear equations?
90pi
67 - 71 - 73
The point of intersection of the systems.
The sum of its digits is divisible by 3.

20. What are 'Supplementary angles?'
Two angles whose sum is 180.
.0004809 X 10^11
90
(a - b)^2

21. What is a set with no members called?
6
The empty set - denoted by a circle with a diagonal through it.
Even
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)

22. What does the graph x^2 + y^2 = 64 look like?
Members or elements
A circle centered on the origin with radius 8.
Lies opposite the greater angle
F(x + c)

23. 0^0
Undefined
The set of elements which can be found in either A or B.
Its last two digits are divisible by 4.
Lies opposite the greater angle

24. Area of a triangle?
6 : 1 : 2
4.25 - 6 - 22
(base*height) / 2
5 OR -5

25. 10^6 has how many zeroes?
N! / (k!)(n-k)!
1/a^6
6
2

26. Legs 5 - 12. Hypotenuse?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
N! / (n-k)!
(a + b)^2
13

27. If r - t - s & u are distinct - consecutive prime numbers - less than 31 - which of the following could be an average of them (4 - 4.25 - 6 - 9 - 24 - 22 - 24)
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
61 - 67
4.25 - 6 - 22
18

28. How to determine percent decrease?
(amount of decrease/original price) x 100%
Relationship cannot be determined (what if x is negative?)
(a - b)^2
1:sqrt3:2

29. What is a finite set?
A set with a number of elements which can be counted.
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
500

30. How many 3-digit positive integers are even and do not contain the digit 4?
1
288 (8 9 4)
Ax^2 + bx + c where a -b and c are constants and a /=0
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

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?
F(x-c)
10! / 3!(10-3)! = 120
1:sqrt3:2
(a - b)(a + b)

32. P and r are factors of 100. What is greater - pr or 100?
12.5%
$11 -448
1.0843 X 10^11
Indeterminable.

33. Define a 'monomial'
An arc is a portion of a circumference of a circle.
An expression with just one term (-6x - 2a^2)
Members or elements
3sqrt4

34. Formula to find a circle'S circumference from its radius?
C = 2(pi)r
37.5%
90pi
1

35. In a regular polygon with n sides - the formula for the sum of interior angles
All numbers multiples of 1.
The curve opens downward and the vertex is the maximum point on the graph.
.0004809 X 10^11
(n-2) x 180

36. Can you add sqrt 3 and sqrt 5?
The set of output values for a function.
II
No - only like radicals can be added.
1

37. 70 < all primes< 80
67 - 71 - 73
71 - 73 - 79
61 - 67
A reflection about the axis.

38. The larger the absolute value of the slope...
Lies opposite the greater angle
4:5
The steeper the slope.
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.

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 direction of the inequality is reversed.
N! / (n-k)!
Move the decimal point to the right x places
The empty set - denoted by a circle with a diagonal through it.

40. What is the graph of f(x) shifted downward c units or spaces?
The second graph is less steep.
F(x) - c
y = (x + 5)/2
Divide by 100.

41. Which quandrant is the lower right hand?
An infinite set.
I
6 : 1 : 2
IV

42. Formula of rectangle where l increases by 20% and w decreases by 20%
83.333%
Diameter(Pi)
x= (1.2)(.8)lw
75:11

43. 5x^2 - 35x -55 = 0
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
31 - 37
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Infinite.

44. What is the ratio of the sides of a 30-60-90 triangle?
1:sqrt3:2
72
The objects within a set.
Angle/360 x 2(pi)r

45. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
$3 -500 in the 9% and $2 -500 in the 7%.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
An arc is a portion of a circumference of a circle.
0

46. What is the graph of f(x) shifted left c units or spaces?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
A central angle is an angle formed by 2 radii.
F(x + c)

47. What number between 70 & 75 - inclusive - has the greatest number of factors?
A circle centered on the origin with radius 8.
Undefined
72
Sector area = (n/360) X (pi)r^2

48. Legs: 3 - 4. Hypotenuse?
5
2
2^9 / 2 = 256
(amount of decrease/original price) x 100%

49. How many multiples does a given number have?
67 - 71 - 73
Infinite.
The set of output values for a function.
A = pi(r^2)

50. 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?
75:11
Divide by 100.
The two xes after factoring.
A reflection about the origin.