Remember:
( )(
2
X
4+3
(2)(3)
) Two parentheses together indicate
multiplication.
Exponents fall into the
category of multiplication.
Fractions represent division.
Compute the top and bottom
completely, then divide.
X2
4+3
(2)(3)
Exponents fall into the
category of multiplication.
Fractions represent division.
Compute the top and bottom
completely, then divide.
e.g. 4+3 = 7
(2)(3)= 6
7  6 = 1.67
The Summation Sign
 :
X
a symbol for summing
all values that are to the right
of the symbol.
represents adding every value that
X can be.
of the symbol.
X
represents adding every value that
X can be.
Data set:
2, 4, 6, 8
X = 2 + 4 + 6 + 8
X = 20
Using that same data set:
2, 4, 6, 8
X
2
X
2
=
=
X =
2
(2x2) + (4x4) + (6x6) + (8x8)
4 + 16 + 36 + 64
120
What is the difference between
XY
and
XY
Imagine you were using these two
data sets:
X:
2, 4, 6, 8
Y:
1, 3, 5, 7
XY
= (2+4+6+8)(1+3+5+7)
= (20)(16)
=
320
data sets:
XY
= (2+4+6+8)(1+3+5+7)
X:
2, 4, 6, 8
= (20)(16)
Y:
=
XY
1, 3, 5, 7
320
XY
= (2+4+6+8)(1+3+5+7)
=
(2x1)+(4x3)+(6x5)+(8x7)
= (20)(16)
=
2 + 12= + 320
30 + 56
= XY
100 =
=
(2x1)+(4x3)+(6x5)+
2 + 12 + 30 + 56