\(-115-\left(17+2x\right)=20\)

\(=>17+2x=\left(-115\right)-20\)

\(=>17+2x=-135\)

\(=>2x=\left(-135\right)-17\)

\(=>2x=-152\)

\(=>x=\left(-152\right):2\)

\(=>x=-76\)

a) \(16,7\times2,5-6,7\times2,5\)

\(=2,5\times\left(16,7-6,7\right)\)

\(=2,5\times10=25\)

b) \(4,65\times5,7+5,7\times5,35\)

\(=5,7\times\left(4,65+5,35\right)\)

\(=5,7\times10=57\)

\(#NgHahh\)

Giáo dục địa phương - Kon Tum. _{( Vì mình không thấy môn học này nên mình chọn môn học có liên quan )}

Giúp mình với nha. Thanks

Ta có: 

\(10=2.5\)

\(1000=2^3.5^3\)

\(ƯCLN\left(10;1000\right)=2.5=10\)

\(ƯC\left(10;1000\right)=Ư\left(10\right)=\left\{1;2;5;10\right\}\)

Vì \(ƯC\in Z\) nên \(ƯC\in\left\{2;5\right\}\)

1+2+3+4+5+...+15+16+17+18+19+20

= ( 1 + 19 ) + ( 2 + 18 ) + ( 3 + 17 ) + ( 4 + 16 ) + ( 5 + 15 ) + ... + ( 9 + 11 ) +  ( 10 + 20 )

= 20 + 20 + 20 + 20 + ... + 20 + 30

= 180 + 30 = 210

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