a) ( -17 + |91| ) – ( 91 – |-17| – 2011 ) = ( -17 + 91 ) – ( 91 – 17 – 2011 )

= - 17 + 91 – 91 + 17 + 2011 = ( - 17 + 17 ) + (91 – 91 ) + 2011 = 2011

a)  − 3 8 . 2 5 + − 3 8 . 14 5 = − 3.2 8.5 + − 3.14 8.5 = − 3 20 + − 21 20 = − 24 20 = − 6 5 .

b)  − 17 + 91 − 91 − − 17 − 2019 = − 17 + 91 − 91 − 17 − 2019   = − 17 + 91 − 91 + 17 + 2019 = − 17 + 17 + 91 − 91 + 2019 = 2019 ,

a) \(\left(-17+\left|91\right|\right)-\left(91-\left|-17\right|-2011\right)\)

\(=\left(-17+91\right)-\left(91-17-2011\right)\)

\(=74-\left(74-2011\right)\)

\(=74-74+2011\)

\(=0+2011\)

\(=2011\)

b) \(\dfrac{4}{7}+\dfrac{5}{6}:5-0,375.\left(-2\right)^2\)

\(=\dfrac{4}{7}+\dfrac{1}{6}-\dfrac{3}{8}.4\)

\(=\dfrac{24}{42}+\dfrac{7}{42}-\dfrac{3}{2}\)

\(=\dfrac{31}{42}-\dfrac{63}{42}\)

\(=\dfrac{-16}{21}\)

c) \(\left(\dfrac{-17}{11}:\dfrac{5}{12}+\dfrac{-4}{12}:\dfrac{5}{12}\right).2.\dfrac{\left|-5\right|}{3}\)

\(=\left(\dfrac{-17}{11}+\dfrac{-4}{12}\right):\dfrac{5}{12}.\dfrac{2.\left|-5\right|}{3}\)

\(=\left(\dfrac{-204}{132}+\dfrac{-44}{132}\right):\dfrac{5}{12}.\dfrac{2.5}{3}\)

\(=\dfrac{-62}{33}:\dfrac{5}{12}.\dfrac{10}{3}\)

\(=\dfrac{-248}{55}.\dfrac{10}{3}\)

\(=\dfrac{-496}{33}\)

a) 105*x-20-18-16-...-2=19+17+15+...+3+1

105*x=1+2+3+4+...+20

105*x=\(\frac{\left(20+1\right)x20}{2}\)

105*x=210

x=2

Vậy x = 2

b) 1-6+11-16+21-26+...+91-96+101

=101-96+91-86+...+21-16+11-6+1

=(101-96)+(91-86)+...+(21-16)+(11-6)+1

=5+5+...+5+5+1                ( có (101-6):5+1);2=10 số 5)

=5x10+1=51

a)105xX-20-18-16-...-2=19+17+15+...+3+1

105xX-(20+18+16+...+2)=19+17+15+...+3+1

105xX-110=100

105xX=100+110

105xX=210

X=210:105

X=2

= -772

tích nha!!!

a) (83 + 234) - (234 - 17)

= 83 + 234 - 234 - 17

= 83 - 17 = 66

Xin lỗi mấy bạn suốt ngày trả lời '' chtt '' , xin thưa là trong đấy không có !

=\(\frac{6}{37}\)

a)(83+234)-(234-17)=83+234-234+17=(83+17)+(234-234)=100+0=100

b)(401-9876)+(9876-403)=401-9876+9876-403=(401-403)-(9876-9876)=-2+0=-2

c)(91-99-98)-(-99-98)=91-99-98+99+98=91-(99-99)-(98-98)=91-0-0=91