-9

a) a+|a|

=-3+|-3|

=-3+3=0

b) a-|a|

=-3-|-3|

=-3-3=-6

c) a.|a|

=-3.|-3|

=-3.3=-9

a.15-(x-7)=-21

(x-7)=15-(-21)

(x-7)= 36

x = 36+7

x = 43

b.(17-x)-12=6

(17-x) = 6+12

(17-x) = 18

x = 17-18

x = -1

(x+1)+(x+2)+...+(x+2017)=0

=2017x+(1+2++...+2017)=0

=2017x+2017.2018:2=0

=2017x+2035153=0

=>x=-1009

42