Question

Tính :

a) [ 98 + ( - 100 ) + 102 ] . ( - 2 )

b) 245 + [ 37 + ( - 245 ) - | - 17 | ]

c) | 5 | - ( - 5 ) - | - 7 | . 3

d) - ( 2 - 5 ) - 13

e) 334 + ( - 20 ) + ( 2007 - 334 )

f) -1 + 3 - 5 + 7 - 9 + ... + 103

Answer 1

a)[98+(-100)+102].(-2)

=(98-100+102).(-2)

=98-100+102.(-2)

=98-100+(-204)

=-2+(-204)

=-206

b)245+[37+(-245)-|-17|]

=245+(37-245-17)

=245+37-245-17

=245-245+37-17

=0+37-17

=37-17

=20

c)|5|-(-5)-|-7|.3

=5+5-7.3

=5+5-21

=10-21

=11

d)-(2-5)-13

=-2+5-13

=3-13

=-10

e)334+(-20)+(2007-334)

=334-20+2007-334

=334-20-(-2007)-334

=334-334+2007-20

=0+2007-20

=2007-20

=1987

f)-1+3-5+7-9+...+103

=-1+3+(-5)+7+(-9)+...+103
=-2+(-2)+(-2)+...+-2(Có tất cả 51 số -2)

=-2.51

=-102

Xog r` đó