DAT Destroyer QR Flashcards

1
Q

What does the sin (2x) =

A

2 sin x cos x

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2
Q

how do you get rid of a square root in the denominator

A

you multiply the whole thing by the conjugate of the denominator

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3
Q

What do you do for a negative exponent 3^-3

A

you do the inverse of the thing

1/ 3^3

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4
Q

What do you do for a fraction exponent 9^3/2

A
  1. you move the bottom number as a root
    if the bottom number is 2 you do the square root
    if the bottom number is 3 you do the cube root
  2. and you leave the top as an exponent of the new rooted base
9^3/2 = (square root of 9)^3
9^2/3 = (cube root of 9)^2
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5
Q

If you have 8 horses, how many ways can they finish a race in first, second, third

A

n! / (n-r)!
8! / (8-3)! = 8x7x6
Use this when order matters!!!

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6
Q

there are 12 people, how many different groups of three can be made

A

n! / r! x (n-r)!
12! / 3! x 9! = 12x11x10 / 3x2x1
Use this when order doesn’t matter

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7
Q

What is the equation for simple interest

A

I = Prt

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8
Q

Is 1 a prime number?

A

nope

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9
Q

what is the sum of the internal angles of a convex polygon equation

A

sum of the angles, s = (n-2)(180)

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10
Q

what is the secret to this problem

  1. 625 x 10^5
    - ——————
  2. 189 x 10^3
A

you can round to get 3.6/1.2 = 3x10^2

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11
Q

what is the secret to this problem
jane wants to run 25 miles in 5 days. she wants to run one more mile everyday than she did the previous day. How many miles must she run the first day

A

x + (x+1) + (x+2) + (x+3) + (x+4) = 25
5x + 10 = 25
x=3

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12
Q

what does 2(sinx*cosx) =

A

sin 2x

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13
Q

what is the discriminant of a quadratic equation

A

the part under the square root

B^2 - 4ac

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14
Q

what happens when the descriminant is a positive perfect square

A

the roots are real, rational, and distinct

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15
Q

what happens when the discriminant of a square root is a positive non-perfect square

A

the roots are real, irrational, and disticnt

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16
Q

(x+y)(x-y) =

A

x^2 - y^2

17
Q

what is the circumference of a circle in radians

A

2pie Radians

18
Q

what is the doubling equation

A
P = O(2^x/t)
P = population
O = original population
x = time
t = doubling time
19
Q

what is the secret for savings and taxes problems

A

if you are calculating savings. find it and then multiply the taxes in

20
Q

what is - ln 1/4

A

ln 4

21
Q

what does cos^2 x =

A

1- sin^2 x

22
Q

What does sin 2x =

A

2 sinx*cosx

23
Q

What does tan^2x +1 =

A

sec ^2x

24
Q

what does cot^2x + 1 =

A

csc^2x

25
Q

What does ln (aboslute value of (sin/cos) =

A

ln absolute value of sin - ln absolute value of cos

26
Q

what is the secret in what is the area of a circle in terms of it’s circumference

A

you find a common variable and substitute it
A = pie r^2
C = 2pier
r is common, find what r = in C and plug it into A

27
Q

when it asks for the angle of depression what should you look for

A

the angle of depression of what? that shows which angle you are talking about