1. 2000/1000 = 2

5 x 217 x 20 - 4 x 215 x 25 

= 1085 x 20 - 4 x 215 x 25

= 21700 - 4 x 215 x 25

= 21700 - 860 x 25

= 21700 - 21500

= 200

\(5.217.20-4.215.25\)

\(=\left(5.20\right).217-\left(4.25\right).215\)

\(=100.217-100.215\)

\(=100.\left(217-215\right)\)

\(=100.2=200\)

Nhớ k cho mình nhé! thank you!!!

5.217.20 - 4.215.25

=5.20.217 -4.25.215

=100.217 - 100.215

=21700 - 21500

=200

\(\frac{217-x}{207}+\frac{215-x}{209}+\frac{213-x}{211}+\frac{211-x}{213}+4=0\)

\(\Leftrightarrow\)\(\left(\frac{217-x}{207}+1\right)+\left(\frac{215-x}{209}+1\right)+\left(\frac{213-x}{211}+1\right)+\left(\frac{211-x}{213}+1\right)=0\)

\(\Leftrightarrow\)\(\frac{424-x}{207}+\frac{424-x}{209}+\frac{424-x}{211}+\frac{424-x}{213}=0\)

\(\Leftrightarrow\)\(\left(424-x\right)\left(\frac{1}{207}+\frac{1}{209}+\frac{1}{211}+\frac{1}{213}\right)=0\)

\(\Leftrightarrow\)\(424-x=0\)   (do 1/207 + 1/209 + 1/211 + 1/213 # 0)

\(\Leftrightarrow\)\(x=424\)

Vậy...

5 x 217 x 20 - 4 x 215 x 25

= ( 5 x 20 ) x 217 - ( 4 x 25 ) x 215

= 100 x 217 - 100 x 215

= 100 x ( 217 - 215 )

= 100 x 2

= 200

5 x 217 x 20-4 x 215 x 25

=(5 x 20) x 217-(4 x 25) x 215

=100 x 217-100 x 215

=100 x (217-215)

=100 x 2

=200

5 x 217 x 20 - 4 x 215 x 25

= 100 x 217 - 100 x 215

= 100 x (217 - 215)

= 100 x 2

= 200

\(8^5\div8^2=8^{5-2}=8^3=512\)

---> chọn A

xin tiick

câu này sao ko có ai trả lời nhỉ