- operations and brakets

operations and brackets

reminder

1) 9,514 - 1,6

► answer

2) 4,56 x 1,7

► answer

exercise

reckon

3,07 + 11,354 + 0,009

► answer

operatins with brackets

, rule1

when there are brackets , operations inside brackets must be done first

example 1

11-(15-8) = 11 - 7

= 4

example 2

4,25 x [ 17 -( 5+3) x2 ] = 4,25 x [ 17 -8 x2 ]

=4,25 x [ 17 -16 ]

= 4,25 x 1

= 4,25

operatins without brackets

rule 2

when there's no bracket between operations , multiplications and divisions must be done first , then addition and subtractions

example 3

4 + 2×3 = 4 + (2×3) = 4 + 6 = 10

Distributive property

( m + n ) · k = m · k + n · k

► exercises

rules

a - ( b + c ) = a - b - c

a - ( b - c ) = a - b + c

a + ( b + c ) = a + b + c

a + ( b - c ) = a + b - c

( a + b ) ( c - d ) = ac - ad + bc - bd

( a - b ) ( c + d ) = ac + ad - bc - bd

( a + b ) ( c + d ) = ac + ad + bc + bd

( a- b ) ( c- d ) = ac - ad - bc + bd

► exercises