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a) \(19\times\left(52+38\right)-9\times\left(52+38\right)=\)
\(=\) \(19\times90-9\times90\)
\(=90\times\left(19-9\right)\)
\(=90\times10\)
\(=900\)
b) \(\dfrac{2}{5}\div\dfrac{3}{7}\times\dfrac{3}{7}\div\dfrac{2}{5}+2019=\)
\(=\left(\dfrac{2}{5}\div\dfrac{2}{5}\right)\times\left(\dfrac{3}{7}\div\dfrac{3}{7}\right)+2019\)
\(=1\times1+2019\)
\(=2019\)
( 1 + 3 + 5 + 7 +...+ 2019) \(\times\) ( 4848 \(\times\) 75 - 7575 \(\times\) 48):51
=(1 + 3 + 5 + 7 +...+2019)\(\times\)( 48 \(\times\) 101 \(\times\) 75 - 75 \(\times\) 101 \(\times\)48):51
=(1+3+5+7+...+2019) \(\times\) ( 48 \(\times\) 101 \(\times\) 75 - 48 \(\times\) 101 \(\times\) 75):51
=(1+3+5+7...+2019)\(\times\)0 : 51
= 0: 51
= 0
(75*38-150*19):(1+2+3+...+2016)
=(75*38-75*38):(1+2+3+..+2016)
=0:(1+2+3+...+2016)
=0
bn tick cho mk nha
a )
Ta có :
\(A=18\times19=\left(17+1\right)\times19=17\times19+19\)
\(B=17\times20=17\times\left(19+1\right)=17\times19+17\)
Do \(17\times19+19>17\times19+17\)
\(\Rightarrow A>B\)
Vậy \(A>B\)
b )
Ta có :
\(C=2019\times2019=\left(2018+1\right)\times2019=2018\times2019+2019\)
\(D=2018\times2020=2018\times\left(2019+1\right)=2018\times2019+2018\)
Do \(2018\times2019+2019>2018\times2019+2018\)
\(\Rightarrow C>D\)
Vậy \(C>D\)
b) 98 x a + b x 98 - c x 98
= 98 x (a + b - c)
= 98 x 150
= 14700
Phần a hình như sai đề thì phải
~chúc hok tốt ^^~
2019 x 45 + 54 x 2019 + 2019/2019 x 2022 - 2018 x 201
=2019*(45+54+1)-2018
=2019*100-2018
=201900-2018
=199882
2019 x 45 + 54 x 2019 + 2019/2019 x 2022 - 2018 x 201
=2019*(45+54+1)-2018
=2019*100-2018
=201900-2018
=199882