\(28+(-199)+99+72\)
\(=(28+72)+(-199+99)\)
\(=100+(-100)\)
\(=0\)
\(--------\)\(---\)
\((-34)+121+(-66)-21\)
\(=/-34+(-66)/ +(121-21)\)
\(=-100+100\)\(=0\)
\(-------------\)
\((-87)+38-13-138\)
\(=(-87-13)+(138-38)\)
\(=-100+100=0\)
\(----------------\)
\(35+(-67)+65-33\)
\(=(35+65)+(-67-33)\)
\(=100+(-100)\)\(=0\)
\(---------\)
\(=35x(-18)+35x(-82)\)
\(=35x/-18+(-82)/\)
\(=\)\(35x(-100)=-3500\)
Câu 11:
\(28+\left(-199\right)+99+72.\)
\(=\left(28+72\right)+\left[\left(-199\right)+99\right].\)
\(=100+\left(-100\right).\)
\(=0.\)
Câu 12:
\(\left(-34\right)+121+\left(-66\right)-21.\)
\(=\left[\left(-34\right)+\left(-66\right)\right]+\left(121-21\right).\)
\(=\left(-100\right)+100.\)
\(=0.\)
Câu 13:
\(\left(-87\right)+38-13-138.\)
\(=\left[\left(-87\right)-13\right]+\left(138-38\right).\)
\(=\left[\left(-87\right)+\left(-13\right)\right]+\left(138-38\right).\)
\(=\left(-100\right)+100.\)
\(=0.\)
Câu 14:
\(35+\left(-67\right)+65-33.\)
\(=\left(35+65\right)+\left[\left(-67\right)-33\right].\)
\(=\left(35+65\right)+\left[\left(-67\right)+\left(-33\right)\right].\)
\(=100+\left(-100\right).\)
\(=0.\)
Câu 15:
\(35.\left(-18\right)+35.\left(-82\right).\)
\(=35.\left[\left(-18\right)+\left(-82\right)\right].\)
\(=35.\left(-100\right).\)
\(=-3500.\)
Lưu ý: Dấu "." là dấu "x" nha. Còn dấu cuối cùng ý là dấu chấm thôi nha!
