a) 463+318+137+22

 = (463+137)+(318+22)

 =  600+340

 = 940

b) 185.32-32.85

 =  32.(185-85)

 =  32 . 100

 =  3200

c) \(15:\left\{390:\left[500-\left(125+35.7\right)\right]\right\}\)

\(\text{= }15:\left\{390:\left[500-\left(125+245\right)\right]\right\}\)

\(\text{= }15:\left\{390:\left[500-370\right]\right\}\)

\(=15:\left(390:130\right)\)

\(\text{= }15:3\)

\(\text{= }5\)

a)\(463+318+137+22\)

\(=\left(463+137\right)+\left(318+22\right)\)

\(=600+340=940\)

b)\(185.3^2-3^2.85\)

\(=3^2.\left(185-85\right)\)

\(=9.100=900\)

c)\(15:\left\{390:\left[500-\left(125+35.7\right)\right]\right\}\)

\(=15:\left\{390:\left[500-\left(125+245\right)\right]\right\}\)

\(=15:\left\{390:\left[500-370\right]\right\}\)

\(=15:\left\{390:130\right\}\)

\(=15:3=5\)

a) 463 + 318 + 137 + 22 = (463 + 137) + (318 +22) = 600 + 340 = 940

Phương pháp giải:

So sánh các cặp chữ số cùng hàng theo thứ tự từ trái sang phải. 

Lời giải chi tiết:

115 < 119      137 > 130

156 = 156      149 < 152

185 > 179      165 > 156

189 < 194      172 > 170

192 < 200      190 > 158

125 : \(x\) = 2² - (-1)

125 : \(x\) = 4 + 1

125 : \(x\) = 5

        \(x\) = 125 : 5

       \(x\)  = 25

18 - (\(x\) + 14) : 3 = 27

      (\(x\) + 14) : 3 = 18 - 27

      (\(x\) + 14) : 3 = - 9

      \(x\) + 14         = - 9.3

       \(x\) + 14       = -27

       \(x\)               = -27 - 14

        \(x\)              = - 41

2^\(2x\) - mũ 3 là sao em?    = 32

a) 67+135+33=(67+33)+135=100+135=235

b) 277+13+323+87=(277+323)+(113+87)=600+200=800

c) 29+132 + 237 + 868 + 763=29+(132+868)+(237+763)=29+1000+1000=2029

d) 652 + 327 + 148 + 15 + 73=(652+148)+(327+73)+15=800+400+15=1215

e) 463 + 318 + 137 + 22=(463+137)+(318+22)=600+340=940

g) 189 + 424 +511 + 276 + 55=(189+511)+(424+276)+55=700+700+55=1455

h) (321 +27) + 79=(321+79)+27=400+27=427

i) 185+434+515+266+155=(185+515)+(434+266)+155=700+700+155=1555

k) 168 + 79 + 132=(168+132)+79=300+79=379

l) 29 + 132 + 237 + 868 + 763=29+(132+868)+(237+763)=29+1000+1000=2029

4:

a: \(\dfrac{\left(158-x\right)}{7}=20\)

=>\(158-x=7\cdot20=140\)

=>x=158-140=18

b: \(2x-138=23\cdot32\)

=>\(2x-138=736\)

=>2x=736+138=874

=>x=437

c: \(231-\left(x-6\right)=\dfrac{1339}{13}\)

=>\(231-\left(x-6\right)=103\)

=>x-6=128

=>x=128+6=134

d: \(10+2x=\dfrac{45}{43}\)

=>\(2x=\dfrac{45}{43}-10=-\dfrac{385}{43}\)

=>\(x=-\dfrac{385}{43}:2=-\dfrac{385}{86}\)

e: \(70-5\left(2x-3\right)=45\)

=>\(5\left(2x-3\right)=70-45=25\)

=>2x-3=5

=>2x=8

=>x=4

g: \(156-\left(x+61\right)=82\)

=>x+61=156-82=74

=>x=74-61=13

a) 137 x 7 + 137 x 93
= 137 x ( 93 + 7 )
= 137 x 100 = 13700

b) 428 x 102 - 428 x 2
= 428 x ( 102 - 2 )
= 428 x 100
= 42800

c) 124 x 25 - 25 x 24
= 25 x ( 124 - 24 )
= 25 x 100 
= 2500

_HỌC TỐT_
 

a) 137 x 7 + 137 x 93

\(=137\times\left(7+93\right)\\ =137\times100\\ =13700\)

b) 428 x 102 - 428 x 2

\(=428\times\left(102-2\right)\\ =428\times100\\ =42800\)
c) 124 x 25 - 25 x 24

\(=25\times\left(124-24\right)=\\ 25\times100=2500\)

#Châu's ngốc

\(a,137.7+137.93\)

\(=137.\left(7+93\right)\)

\(=137.100=13700\)

\(b,428.102-428.2\)

\(=428.\left(102-2\right)\)

\(=428.100=42800\)

\(c,124.25-25.24\)

\(=25.\left(124-24\right)\)

\(=25.100=2500\)

a) ( (-237)+(-63) ) +( 78 + (-28) )= (-300) +50 = (-250)

b) (-137).26-137+73.(-137)= (-137) . (26+1+73)=(-137).100=-137000

đề bài 2 này chắc em gõ sai đề nhé, vì nếu giữ nguyên đề này thì quá tầm kiến thức 6

Sửa: xy+y=9 <=> y(x+1)=9

ta có bảng sau:

Vậy (x,y)=...

Bài 1 : Tính hợp lí :

a )  (- 237 ) + 78 + ( - 63 ) + ( - 28 )

= [ ( - 237 ) + ( - 63 ) ] + [ 78 + ( - 28 ) ] 

= - 300 + 50

= - 250

`185:0,25+185×95+185`

`=185×4+185×95+185×1`

`=185×(4+95+1)`

`=185×100`

`=18500`

`#Bao`

18500

= 185 x 4 + 185 x 95 + 185 x 1

= 185 x ( 4 + 95 + 1 )
= 185 x 100

= 18500