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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. Formula of rectangle where l increases by 20% and w decreases by 20%
Yes. [i.e. f(x) = x^2 - 1
9 & 6/7
x= (1.2)(.8)lw
8

2. A company places a 6-symbol code on each product. The code consists of the letter T - followed by 3 numerical digits - and then 2 consonants (Y is a conson). How many codes are possible?
(a + b)^2
441000 = 1 10 10 10 21 * 21
The union of A and B.
The interesection of A and B.

3. Simplify 9^(1/2) X 4^3 X 2^(-6)?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
180 degrees
x^(2(4)) =x^8 = (x^4)^2
3

4. 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?
The sum of digits is divisible by 9.
$3 -500 in the 9% and $2 -500 in the 7%.
A reflection about the origin.
The curve opens downward and the vertex is the maximum point on the graph.

5. 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?
Move the decimal point to the right x places
y = 2x^2 - 3
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
10

6. What is the formula for computing simple interest?
Sector area = (n/360) X (pi)r^2
Members or elements
Its divisible by 2 and by 3.
A = I (1 + rt)

7. When does a function automatically have a restricted domain (2)?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Yes - like radicals can be added/subtracted.
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
Cd

8. Formula to find a circle'S circumference from its radius?
An expression with just one term (-6x - 2a^2)
441000 = 1 10 10 10 21 * 21
9 : 25
C = 2(pi)r

9. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
2^9 / 2 = 256
75:11
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
A circle centered at -2 - -2 with radius 3.

10. What is the intersection of A and B?
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
(a + b)^2
The set of elements found in both A and B.
3

11. 25^(1/2) or sqrt. 25 =
1.0843 X 10^11
5 OR -5
1
A 30-60-90 triangle.

12. Legs 6 - 8. Hypotenuse?
x(x - y + 1)
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
10
The set of input values for a function.

13. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
8
A = pi(r^2)
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
90pi

14. 5x^2 - 35x -55 = 0
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
C = (pi)d
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
No - the input value has exactly one output.

15. A cylinder has a surface area of 22pi. If the cylinder has a height of 10 - what is the radius?
Diameter(Pi)
27^(-4)
2^9 / 2 = 256
1

16. Can the output value of a function have more than one input value?
No - only like radicals can be added.
Yes. [i.e. f(x) = x^2 - 1
Members or elements
F(x + c)

17. What does scientific notation mean?
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
Cd
87.5%
11 - 13 - 17 - 19

18. Which is greater? 27^(-4) or 9^(-8)
27^(-4)
y = 2x^2 - 3
A subset.
Angle/360 x (pi)r^2

19. Suppose you have a set of n objects - and you want to select k of them - but the order doesn'T matter. What formula do you use to determine the number of combinations of n objects taken k at a time?
N! / (k!)(n-k)!
The third side is greater than the difference and less than the sum.
Cd
From northeast - counterclockwise. I - II - III - IV

20. Define a 'Term' -
20.5
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
28. n = 8 - k = 2. n! / k!(n-k)!
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)

21. What are 'Supplementary angles?'
A central angle is an angle formed by 2 radii.
Angle/360 x (pi)r^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)

22. 10^6 has how many zeroes?
0
A circle centered at -2 - -2 with radius 3.
6
3

23. Evaluate 3& 2/7 / 1/3
(amount of increase/original price) x 100%
9 & 6/7
288 (8 9 4)
2^9 / 2 = 256

24. A number is divisible by 4 is...
When the function is not defined for all real numbers -; only a subset of the real numbers.
Its last two digits are divisible by 4.
(a - b)(a + b)
(amount of decrease/original price) x 100%

25. 413.03 x 10^(-4) =
1
An arc is a portion of a circumference of a circle.
413.03 / 10^4 (move the decimal point 4 places to the left)
3

26. Describe the relationship between 3x^2 and 3(x - 1)^2
The curve opens upward and the vertex is the minimal point on the graph.
The overlapping sections.
The set of elements which can be found in either A or B.
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

27. Convert 0.7% to a fraction.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
From northeast - counterclockwise. I - II - III - IV
7 / 1000
Undefined - because we can'T divide by 0.

28. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
F(x) - c
Sector area = (n/360) X (pi)r^2
12sqrt2
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

29. Factor a^2 + 2ab + b^2
1
(a + b)^2
2 & 3/7
x^(6-3) = x^3

30. What is the coefficient of the x^2 term in the product of (x + 1)(x + 2)(x -1)?
Cd
10! / 3!(10-3)! = 120
The sum of its digits is divisible by 3.
2

31. Which quadrant is the lower left hand?
III
2
61 - 67
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

32. 7/8 in percent?
x^(4+7) = x^11
Diameter(Pi)
87.5%
An expression with just one term (-6x - 2a^2)

33. 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 reflection about the axis.
10! / 3!(10-3)! = 120
16.6666%
(a - b)(a + b)

34. What are the real numbers?
5 OR -5
F(x-c)
4725
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)

35. What is a subset?
A grouping of the members within a set based on a shared characteristic.
The direction of the inequality is reversed.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Triangles with same measure and same side lengths.

36. How to determine percent decrease?
(a + b)^2
(amount of decrease/original price) x 100%
62.5%
4a^2(b)

37. When the 'a' in a parabola is positive....
The curve opens upward and the vertex is the minimal point on the graph.
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)
The sum of its digits is divisible by 3.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)

38. Volume for a cylinder?
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.
1 & 37/132
Area of the base X height = (pi)hr^2
12.5%

39. 4.809 X 10^7 =
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
.0004809 X 10^11
(n-2) x 180
A circle centered at -2 - -2 with radius 3.

40. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
An infinite set.
1:sqrt3:2
28. n = 8 - k = 2. n! / k!(n-k)!

41. 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)?
The objects within a set.
4a^2(b)
The set of input values for a function.
y = (x + 5)/2

42. How to determine percent increase?
3sqrt4
(amount of increase/original price) x 100%
Its last two digits are divisible by 4.
1

43. If an inequality is multiplied or divided by a negative number....
6
90 degrees
The sum of its digits is divisible by 3.
The direction of the inequality is reversed.

44. What is the 'Range' of a function?
(a - b)^2
9 : 25
1
The set of output values for a function.

45. (-1)^2 =
Factors are few - multiples are many.
1
9 & 6/7
3

46. Area of a triangle?
The longest arc between points A and B on a circle'S diameter.
(base*height) / 2
Sector area = (n/360) X (pi)r^2
1

47. Pi is a ratio of what to what?

48. Define an 'expression'.
The set of elements found in both A and B.
52
.0004809 X 10^11
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)

49. What is the slope of a vertical line?

50. Which quandrant is the lower right hand?
1
The sum of its digits is divisible by 3.
IV
All numbers multiples of 1.