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a ) 128 . ( 278 - 302 ) + 278 . ( 302 - 128 )
= 128 . 278 - 128 . 302 + 278 . 302 - 128 . 278
= ( 128 . 278 - 128 . 278 ) + ( 278 . 302 - 128 . 302 )
= 302 . ( 278 - 128 )
= 302 . 100 = 30200 .
b ) 2 . ( - 7 )2 - 3 . ( - 4 )3 - 60
= 2 . 49 + 192 - 60
= 98 + 192 - 60
= 230 .
Bài 1:
a) \(128\cdot\left(278-302\right)+278\cdot\left(302-142\right)\)
\(=128\cdot278-128\cdot302+278\cdot302-278\cdot142\)
\(=41408\)
b) \(\left(-2\right)\cdot\left(-6\right)^2+3\cdot\left(-2\right)^3-62\)
\(=\left(-2\right)-36-24-62=-2-36-24-62=-124\)
c) \(1152-\left(374+1152\right)+\left(-65+374\right)\)
\(=1152-374-1152-65+374=-65\)
d) \(-215\cdot54-430\cdot23=-215\cdot54-215\cdot46=-215\left(54+46\right)=-215\cdot100=-21500\)
e) \(\left(-2\right)+\left(-49\right)+\left(-18\right)+49=-20\)
\(A=5+8+...+302\)
\(=\frac{\left(5+302\right)\left[\left(302-5\right):3+1\right]}{2}\)
\(=\frac{30700}{2}=15350\)
\(B=7+11+15+...+203\)
\(=\frac{\left(7+203\right)\left[\left(203-7\right):4+1\right]}{2}\)
\(=\frac{10500}{2}=5250\)
\(\left(x-278\right).26=0\)
\(x-278=0:26\)
\(x-278=0\)
\(x=278\)
\(\left(x-278\right).26=0\)
\(x-278=0:26\)
\(x-278=0\)
\(x=0+278\)
\(x=278\)
128 = 27
1000 = 23.25
=> ƯCLN(128; 1000) = 23 = 8
=> ƯC(128; 1000) = Ư(8)
=> ƯC(128; 1000) = {1; 2; 4; 8}
128.(278-302)+278.(302-128)
=128.278-128.302+278.302-278.128
=128.278-278.128-128.302+278.302
=302.(128+278)
=302.406
=122612
Chúc bn học tốt
Nguyễn Trí Nghĩa sai rồi ạ!!