1)tính
a)\(-18+\left(-19\right)+27\)
\(=-18-19+27\)
\(=-\left(18+19\right)+27\)
\(=-37+27\)
\(=-\left(37-27\right)\)
\(=-10\)
b)\(-198-194+286\)
\(=-\left(198+194\right)+286\)
\(=-392+286\)
\(=-\left(392-286\right)\)
\(=-6\)
c)\(-19-\left(-17\right)\)
\(=-19+17\)
\(=-\left(19-17\right)\)
\(=-2\)
d)\(-48+\left(-47\right)-\left(-15\right)\)
\(=-48-47+15\)
\(=-\left(48+47\right)+15\)
\(=-95+15\)
\(=-\left(95-15\right)\)
\(=-80\)
e)\(23-\left(-16\right)+\left(-80\right)\)
\(=23+16-80\)
\(=39-80\)
\(=-80+39\)
\(=-\left(80-39\right)\)
\(=-41\)
f)\(99-\left(-99\right)-198\)
\(=99+99-198\)
\(=198-198\)
\(=0\)
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a. =-10
b. =-106
c. =-2
d. =-80
e. =-41
f. =0
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