a) \(-70+70\)
\(=-\left(70-70\right)\)
\(=-0\)
\(=0\)
c) \(\left(-11\right)+\left(-22\right)+\left(-33\right)\)
\(=-11-22-33\)
\(=-\left(11+22\right)-33\)
\(=-33-33\)
\(=-\left(33+33\right)\)
\(=-66\)
d) \(-840+560+\left(-160\right)\)
\(=-840+560-160\)
\(=-\left(840-560\right)-160\)
\(=-280-160\)
\(=-\left(280+160\right)\)
\(=-440\)
\(-99+98+\left(-97\right)+96+\left(-95\right)+94+\left(-93\right)+92+\left(-91\right)+90\)
\(=-99+98-97+96-95+94-93+92-91+90\)
\(=-\left(99-98\right)-\left(97-96\right)-\left(95-94\right)-\left(93-92\right)-\left(91-90\right)\)
\(=-1-1-1-1-1\)
\(=-\left(1+1\right)-1-1-1\)
\(=-2-1-1-1\)
\(=-\left(2+1\right)-1-1\)
\(=-3-1-1\)
\(=-\left(3+1\right)-1\)
\(=-4-1\)
\(=-\left(4+1\right)\)
\(=-5\)
−99+98+(−97)+96+(−95)+94+(−93)+92+(−91)+90−99+98+(−97)+96+(−95)+94+(−93)+92+(−91)+90
=−99+98−97+96−95+94−93+92−91+90=−99+98−97+96−95+94−93+92−91+90
=−(99−98)−(97−96)−(95−94)−(93−92)−(91−90)=−(99−98)−(97−96)−(95−94)−(93−92)−(91−90)
=−1−1−1−1−1=−1−1−1−1−1
=−(1+1)−1−1−1=−(1+1)−1−1−1
=−2−1−1−1=−2−1−1−1
=−(2+1)−1−1=−(2+1)−1−1
=−3−1−1=−3−1−1
=−(3+1)−1=−(3+1)−1
=−4−1=−4−1
=−(4+1)=−(4+1)
=−5