Flashcards in Algebra Deck (12)

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1

## equivalent transformation of inequality: x> y + a

### x + a > y +a

2

## important inequality with absolute values

### |X + Y| <= |X| + |Y|

3

## sequence

### a list of objects separated by comma

4

## arithmetic sequence (what is it)

### An=A1 + d(n-1); d - common difference = An-An-1

5

## the same of the first n terms of an arithmetic sequence

### Sn=(A1+An)/2 X n or Sn=(2A1+d(n-1))/2 X n

6

## geometric sequence

###
the riot between any two consecutive terms is the same.

An/An-1 = Q; An=An-1 X Q

7

## geometric sequence of nth term

### An=A1 X Q^(n-1)

8

## sometimes a problem will provide two inequalities and ask you to combine them in some way

###
How to solve:

2 < X < 5; 3

find max and min:

5-3=2 (max)

2-3=-1

2-10= -8 (min)

5-10= -5

Finally: -8

9

## absolute values: if a >0

### |X|=a -> X = a or X= -a.

10

## absolute values: if |X| < a

### -a -3 0

11

## absolute values: if |X| > a

### or X>A or X |X-3| > 3 -> X-3>3 or X-3 or X>6 or X<0

12