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!!

\(45300\)

cách làm cơ bạn

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/128.(278-302)+278.(302-142)

=128(-24)+278.160

=-3072+44480

=41408

b/(-2).(-6)²+3.(-2)³-62

=-2.(-36)+3.(-8)-62

=72+(-24)-62

=48-62

=-14

   \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)......\left(1-\frac{1}{2017}\right)\)

\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}........\frac{2016}{2017}\)

\(=\frac{1}{2017}\)

a)300

b)374

c)4747

d)4530

e)2250

g)123123

Đây là toán lớp 4

a) 300

b) 374

c) 4747

d) 4530

e) 2250

g) 123123

tính  

28.112-28.12+31

=28.(112-12)+31

=28.100+31

=2800+31

=2831

tim x  

42 + 2(x-7) =128

2(x-7)=86

x-7=43

x=50

Tính nhanh : 

 a, 28.112-28.12+31

=28.(112-12)+31

=28.100+31

=2800 + 31

=2831

tìm x : 

a, 42+2.(x-7)=128

2.(x+7)=128-42

2.(x+7)=86

x+7=86:2

x+7=43

x=43-7

x=36

Vậy x=36

4x - 15 = - 75 - x

=> 4x + x = - 75 + 15

=> 5x = - 50

=> x =  -10

Vậy x = -10

2x . ( x - 3 ) = 0

\(\Rightarrow\orbr{\begin{cases}2x=0\\x-3=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x=3\end{cases}}\)

Vậy \(x\in\left\{0;3\right\}\)

Học tốt

K cần tk

4.x-15=-75-x <=> 5.x=-60 <=> x=-12

2.x.(x-3)=0 <=> x=0 hoặc x-3=0

                  <=>x=0 hoặc x=3