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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. How to find the diagonal of a rectangular solid?
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
The set of input values for a function.
Ax^2 + bx + c where a -b and c are constants and a /=0

2. Can the output value of a function have more than one input value?
Two angles whose sum is 180.
When the function is not defined for all real numbers -; only a subset of the real numbers.
441000 = 1 10 10 10 21 * 21
Yes. [i.e. f(x) = x^2 - 1

3. Legs: 3 - 4. Hypotenuse?
Undefined
IV
1/2 times 7/3
5

4. Convert 0.7% to a fraction.
$3 -500 in the 9% and $2 -500 in the 7%.
7 / 1000
The point of intersection of the systems.
Yes. [i.e. f(x) = x^2 - 1

5. 30< all primes<40
31 - 37
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
6

6. Is 0 even or odd?
Even
Indeterminable.
The point of intersection of the systems.
1.7

7. What is the graph of f(x) shifted downward c units or spaces?
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
1 & 37/132
F(x) - c
2.592 kg

8. x^2 = 9. What is the value of x?
The third side is greater than the difference and less than the sum.
An expression with just one term (-6x - 2a^2)
3 - -3
The sum of its digits is divisible by 3.

9. Solve the quadratic equation ax^2 + bx + c= 0
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
288 (8 9 4)
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
55%

10. What is the 'domain' of a function?
The set of input values for a function.
An expression with just one term (-6x - 2a^2)
Two angles whose sum is 180.
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)

11. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
10! / 3!(10-3)! = 120
0
Sqrt 12
x^(6-3) = x^3

12. What are the smallest three prime numbers greater than 65?
87.5%
When the function is not defined for all real numbers -; only a subset of the real numbers.
67 - 71 - 73
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

13. Circumference of a circle?
Diameter(Pi)
62.5%
The overlapping sections.
No - only like radicals can be added.

14. Area of a triangle?
Move the decimal point to the right x places
(base*height) / 2
12.5%
IV

15. What is the 'union' of A and B?
x^(6-3) = x^3
The set of elements which can be found in either A or B.
A subset.
All numbers multiples of 1.

16. How to find the area of a sector?
The second graph is less steep.
Angle/360 x (pi)r^2
12sqrt2
Pi is the ratio of a circle'S circumference to its diameter.

17. 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?
A circle centered on the origin with radius 8.
The empty set - denoted by a circle with a diagonal through it.
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)
y = 2x^2 - 3

18. Whats the difference between factors and multiples?
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
Factors are few - multiples are many.
61 - 67
23 - 29

19. Suppose that the graph of f(x) is the result of stretching y=x + 5 away from the x-axis by a factor of 2. What is the new equation for the graph f(x)?
16.6666%
A reflection about the origin.
71 - 73 - 79
y = (x + 5)/2

20. sqrt 2(sqrt 6)=
F(x-c)
No - the input value has exactly one output.
Sqrt 12
(12/2) x (sqrt15 / sqrt5) = 6sqrt3

21. Define a 'monomial'
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.
3 - -3
Sector area = (n/360) X (pi)r^2
An expression with just one term (-6x - 2a^2)

22. How many sides does a hexagon have?
The steeper the slope.
6
A set with a number of elements which can be counted.
The objects within a set.

23. Which quadrant is the upper left hand?
II
Its divisible by 2 and by 3.
500
52

24. To convert a decimal to a percent...
...multiply by 100.
1:1:sqrt2
The overlapping sections.
180 degrees

25. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
Infinite.
4:5
10! / 3!(10-3)! = 120
IV

26. 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
67 - 71 - 73
13
Angle/360 x 2(pi)r

27. What is a set with no members called?
A chord is a line segment joining two points on a circle.
2sqrt6
The empty set - denoted by a circle with a diagonal through it.
9 : 25

28. To multiply a number by 10^x
All numbers multiples of 1.
3sqrt4
N! / (n-k)!
Move the decimal point to the right x places

29. A triangle is inscribed in a semi circle with legs 5 and 12. What is the circumfermence of the semicircle?
3/2 - 5/3
13pi / 2
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
The objects within a set.

30. 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?
N! / (n-k)!
180
When the function is not defined for all real numbers -; only a subset of the real numbers.
1/2 times 7/3

31. What is the coefficient of the x^2 term in the product of (x + 1)(x + 2)(x -1)?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
9 & 6/7
2
The steeper the slope.

32. Can you add sqrt 3 and sqrt 5?
No - only like radicals can be added.
Two angles whose sum is 90.
1.7
71 - 73 - 79

33. When does a function automatically have a restricted domain (2)?
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
Divide by 100.
53 - 59
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.

34. x^(-y)=
y = 2x^2 - 3
1/(x^y)
83.333%
31 - 37

35. What are the real numbers?
90
I
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)
1

36. Employee X is paid 19.50 per hour no matter how many a week. Employee Y earns 18 for the first 40 and 1.5 the hourly wage for every hour after that. If both earned the same amount and worked the same in one week - how many did each work?
Yes. [i.e. f(x) = x^2 - 1
9 & 6/7
48
The set of output values for a function.

37. What are the roots of the quadrinomial x^2 + 2x + 1?
A grouping of the members within a set based on a shared characteristic.
The two xes after factoring.
y = 2x^2 - 3
72

38. 4.809 X 10^7 =
No - the input value has exactly one output.
.0004809 X 10^11
Its last two digits are divisible by 4.
130pi

39. Length of an arc of a circle?
Angle/360 x 2(pi)r
N! / (k!)(n-k)!
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
1

40. The perimeter of a square is 48 inches. The length of its diagonal is:
(amount of increase/original price) x 100%
A circle centered at -2 - -2 with radius 3.
Pi is the ratio of a circle'S circumference to its diameter.
12sqrt2

41. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
The greatest value minus the smallest.
Cd
II
9 : 25

42. Which is greater? 27^(-4) or 9^(-8)
31 - 37
A central angle is an angle formed by 2 radii.
27^(-4)
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15

43. 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
23 - 29
3
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

44. Write 10 -843 X 10^7 in scientific notation
1.0843 X 10^11
Arc length = (n/360) x pi(2r) where n is the number of degrees.
90
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)

45. Hector invested $6000. Part was invested in account with 9% simple annual interest - and the rest in account with 7% simple annual interest. If he earned $490 in the first year of these investments - how much did he invest in each account?
3
10! / 3!(10-3)! = 120
Two equal sides and two equal angles.
$3 -500 in the 9% and $2 -500 in the 7%.

46. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
9 : 25
A reflection about the axis.
16.6666%

47. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
4:5
70
2^9 / 2 = 256

48. Formula to find a circle'S circumference from its radius?
(a + b)^2
C = 2(pi)r
Pi is the ratio of a circle'S circumference to its diameter.
Yes - like radicals can be added/subtracted.

49. A cylinder has a surface area of 22pi. If the cylinder has a height of 10 - what is the radius?
3 - -3
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
1
0

50. 8.84 / 5.2
3sqrt4
41 - 43 - 47
1.7
Diameter(Pi)