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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) ( -17 + |91| ) – ( 91 – |-17| – 2011 )
= ( -17 + 91 ) – ( 91 – 17 – 2011 )
= - 17 + 91 – 91 + 17 + 2011
= ( - 17 + 17 ) + (91 – 91 ) + 2011 = 2011
a) \(=\left(278+622\right)+\left(809-209\right)=900+600=1500\)
b) \(=64.57+64.43-2300=64\left(57+43\right)-2300=54.100-2300=5400-2300=3100\)
a) 278+809+622-209
= (278+622)+(809-209)
= 900 + 600
= 1500
b) 64.57+64.43-2300
= 64(57+43)-2300
= 64.100-2300
= 6400-2300=4100
c) 24.5-[131-(13-4)2]
= 24.5-(131-9.2)
= 120-113= 7
\(A=\dfrac{5}{11}.\dfrac{5}{7}+\dfrac{5}{11}.\dfrac{2}{7}+\dfrac{6}{11}=\dfrac{5}{11}\left(\dfrac{5}{7}+\dfrac{2}{7}\right)+\dfrac{6}{11}=\dfrac{5}{11}.1+\dfrac{6}{11}=\dfrac{5}{11}+\dfrac{6}{11}=\dfrac{11}{11}=1\)
\(B=\dfrac{3}{13}.\dfrac{6}{11}+\dfrac{3}{13}.\dfrac{9}{11}-\dfrac{3}{13}.\dfrac{4}{11}=\dfrac{3}{13}\left(\dfrac{6}{11}+\dfrac{9}{11}-\dfrac{4}{11}\right)=\dfrac{3}{13}.1=\dfrac{3}{13}\)
\(C=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right)\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{6}\right)=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right)\left(\dfrac{3}{6}-\dfrac{2}{6}-\dfrac{1}{6}\right)=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right).0=0\)
a) ( -17 + |91| ) – ( 91 – |-17| – 2011 ) = ( -17 + 91 ) – ( 91 – 17 – 2011 )
= - 17 + 91 – 91 + 17 + 2011 = ( - 17 + 17 ) + (91 – 91 ) + 2011 = 2011
A=(1278-278)+(722-522)
=1000+200
=1200
B=(1-3)+(5-7)+...+(97-99)+101
=(-2)+(-2)+...+(-2)+101
=(-2).25+101
=(-50)+101
=51
A= (1278-278)+(722-522)
=1000+200
=1200
B=(1-3)+(5-7)+...+(97-99)+101
=(-2)+(-2)+...+(-2)+101
=-2.25+101
=-50+101
=51
A=-100