\(\left(100+58\right)\times58+\left(200-42\right)\times12\)

\(=158\times58+158\times12\)

\(=158\times\left(58+12\right)\)

\(=158\times70=11060\)

\(128\times72+14\times256\)

\(=128\times72+14\times2\times128\)

\(=128\times\left(72+28\right)\)

\(=128\times100=12800\)

\(157\times99+123+34\)

\(=157\times99+157\times1\)

\(=157\times\left(99+1\right)\)

\(=157\times100=15700\)

\(67+98\times45+23\)

\(=98\times45+90\)

\(=98\times45+45\times2\)

\(=45\times\left(98+2\right)\)

\(=45\times100=4500\)

x + x + x + x + 45 = 127 - 58

x . 4 + 45 = 69

x.4 = 69 - 45 = 24 

x = 24 : 4 

x = 6 

x*4+45=69

x*4=69-45

x*4=24

x=24:4

x=6

\(x+x+x+x+45=127-58\)

\(x+x+x+x+45=69\)

\(x+x+x+x=69-45\)

\(4\cdot x=24\)

\(x=6\)

62 . 58 = (60 + 2)(60 - 2) = 60\(^2\) - 2\(^2\) = 3600 - 4 = 3596

199\(^2\) = (200 -1)\(^2\) = 200\(^2\) - 2.200.1 + 1\(^2\) = 40 000 - 400 + 1 = 39601

499\(^2\) = (500 - 1)\(^2\) = 500\(^2\) - 2.500.1 + 1\(^2\) = 250 000 - 1000 + 1 = 249 001

299 . 301 = (300 - 1)(300 + 1) = 300\(^2\) - 1\(^2\) = 90 000 - 1 = 89 999

Học tốt

Đúng thì k cho mk nhé

Trả lời:

+, \(62.58=\left(60+2\right)\left(60-2\right)=60^2-2^2=3600-4=3596\)

+, \(199^2=\left(200-1\right)^2=200^2-2.200.1+1^2=40000-400+1=39601\)

+, \(499^2=\left(500-1\right)^2=500^2-2.500.1+1^2=250000-1000+1=249001\)

+, \(299.301=\left(300-1\right)\left(300+1\right)=300^2-1=90000-1=89999\)

62 * 58  =   ( 60 + 2 ) * ( 60 - 2 ) = 60^2  -  2^2  =  3600 - 4 = 3596

199^2   =  ( 200 - 1 )^2 = 200^2  - 2 * 200 * 1 + 1^2 =  40000 - 400 + 1 = 39601

499^2  =  (  500  - 1 )^2  =  500^2 - 2* 500 *1  + 1^2  =  250000 - 1000 + 1 = 249001

299 * 301=  (  300 - 1 ) * ( 300 + 1 ) = 300^2 - 1^2  = 90000 - 1 = 89999

ad ko biết nha

nhân hết ra là xong nha 

a)  85x35-85x27-35x85+35x27=27x(35-85)=-1350

mấy cái kia cũng tương tự v 

_Kudo_

=85.35-85.27-35.85+35.27

=85.35+85.(-27)-35.85+35.27

=85[35+(-27)+(-35)]+35.27

=85.(-27)+35.27

=-85.27+35.27

=27.[(-85)+35]

=27.(-50)

=-1350

x + 45 = 58

x        = 58 - 45

x        = 13

x + 78 = 90

x         = 90 - 78

x         = 12

x+45=58
x     =58-45
x     =13

x+78=90
x     =90-78
x     =12    

x+45=58

x=58-45

x=13

x+78=90

x=90-78

x=12

a.35 x 34 + 35 x 38 + 65 x 75 + 45 x 65

= 35 x (34 + 38) + 65 x 75 + 65 x 45

= 35 x     72      + 65 x (75+45)

= 35 x 72 + 65 x 120

= 35 x 72 + 65 x (72 + 48)

= 35 x 72 + 65 x 72 + 65 x 48

= (35+65) x 72 + 65  x 48

=   100 x 72 + 65 x 48

=      7200   +    3120

=           10320

b.39 x 8 + 60 x 2 + 21 x 8

=39 x 8 + 15 x 4 x 2 +21 x 8

= 39 x 8 + 15 x 8 + 21 x 8

=(39 + 15 + 21) x 8

=      75            x 8

=             600

c.58 x 75 + 58 x 50 - 58 + 25

= 58 x 75 + 58 x 50 - 58 x 1 + 25

= 58 x(75+50-1)+25

= 58 x   124     + 25

=    7192          + 25

=              7217

d.125 x 98 - 125 x 46 - 52 x 25

= 25 x 5 x 98 - 25 x 5 x 46 - 25 x 52

= 25 x 490 - 25 x 230 - 25 x 52

= 25 x (490 - 230 - 52)

= 25 x      208

=       5200

ham mo chi qua

45-58+(-45)-|-58|-3

=45-58-45-58-3

=(45-45)-(58+58)-3

=0-116-3

=-119

tk cho mk nha! 

bằng

45-58+(-45)-58-3

=[45+(-45)]+[-58+58] -3

=0+0-3

=-3

45 - 58 +(-45)-/-58/ - 3

= 45 - 58 +(-45)- 58 - 3

=[45 + (-45)] + [ - 58 + 58] - 3

= - 3

học tốt 

#mọt

\(S=\left(1+4\right)+\left(4^2+4^3\right)+...+\left(4^{98}+4^{99}\right)\\ S=\left(1+4\right)+4^2\left(1+4\right)+...+4^{98}\left(1+4\right)\\ S=\left(1+4\right)\left(1+4^2+...+4^{98}\right)=5\left(1+4^2+...+4^{98}\right)⋮5\)

\(S=\left(1+4\right)+...+4^{98}\left(1+4\right)\)

\(=5\left(1+...+4^{98}\right)⋮5\)

B)x+36=98

X=98-36

X=62

C)58-x+32=45

58-x=45-32

58-x=13

X=58-13

X=45

a) 36x - 54 = 18

     36x        = 18 + 54

     36x        = 72

         x        = 2

b) x + 36 = 98

     x        = 98 - 36

     x        = 62

c) 58 - x + 32 = 45 

    58 - x         = 45 - 32

     58 - x        = 13

             x        = 58 - 13

             x         = 45

a)  36x - 54 = 18

     36x         = 18 + 54 = 72

         x         =  72 : 36 = 2

vậy x = 2.

b)   x + 36 = 98

      x          = 98 - 36 = 62

      vậy x = 62.

c)   58 - x + 32 = 45

      58 - x         = 45 - 32 = 13

             x          = 58 - 13 = 45

       vậy x = 45.