Tính nhanh:

a, 35x18 -5.7x28 = 35x18 -35x28 = 35 x (18 – 28) = 35 x ( -10) = -350

b,24x(16-5)-16x(24-5) = 24x16 – 24 x 5- 16x24 + 16x5 = (– 24 + 16)x 5 = -8 x 5 = -40

d,31x(-18)+31x(-81)-31 = 31x (-18  -81 – 1) =  31 x (-100) = -3100

e,(-12)x47+(-12)x52+(-12) = (-12)x (47+52 + 1)= (-12)x 100= - 1200

Ý c chưa rõ đề bài...

\(a.35\times18-5.7\times28\)

\(=35.18-35.28\)

\(=35.\left(18-28\right)\)

\(=35.\left(-10\right)\)

\(=-350\)

\(b.24.\left(16-5\right)-16.\left(24-5\right)\)

\(=24.16-24.5-16.24-16.5\)

\(=\left(24.16-16.24\right)-24.5-16.5\)

\(=0-\left(24+16\right).5\)

\(=0-40.5\)

\(=0-200\)

\(=-200\)

Ôi sr bn, câu b tớ nhầm dấu

24.(16-5)-16.(24-5)=24.16-24.5-16.24+16.5

                           =(24.16-24.16)-5.(24-16)

                           =-5.8=-40

Giải luôn nhé!

= 24 x 16 - 5 - 16 x 24 - 5 

= 24 x    11   -     24 x 16 - 5

= 24 x 11      -     24 x    11

=                0

a,  45 - 45 . ( -12 + 3 )

= 45 - 45 . (-9)

= 45 -(- 405)

=450

b,  31 . ( -18 ) + 31 . ( - 81 ) - 31

= 31. [ -18 + (-81 ) - 1 ]

= 31. (-100)

= -3100

d,   ( - 12 ) . 47 + ( - 12 ) . 52 + ( - 12 )

= ( - 12 ) . ( 47 + 52 + 1 )

= ( - 12 ) . 100

= - 1200 

c,  24. ( 16 - 5 ) - 16 . ( 24 - 5 )

 = 24 . 11 - 16 . 19

= 264 - 304

= - 140

Trl

-Bạn kia làm đúng rồi nhé ~!

Chúc bạn học tốt

#Mưaa

a.x+8=âm 17

   x    = - 17 - 8

   x    = -25

b. ( x - 7 ) + 13 = 25

    ( x - 7 )        = 25 - 13

    ( x - 7 )        = 12

      x               = 12 + 7

      x               = 19

1,

a,35*18-5*7*28=35*18*35*28

                     =35*(18-28)

                     =35*  -10

                     =  -350

c.(x+5)x(x-4)=0

==> x = - 5 hoặc x = 4

ai giúp tui đi

B1

a.35*18-5*7*28

=35*18-35*28

=35*(-10)

=-350

b.24*(16-5)-16*(24-5)

=(24*16)-24*5-(16*24)-16*5

=384-24*5-384-16*5

=(384-384)-24*5-16*5

=0-24*5-16*5

=5*(-24-16)

=5*(-8)

=-40

c.29*(19-23)-19*(29-13)

=(29*19)-(19*29)*23-13

=(551-551)*23-13

=0*10

=0

d.34+35+36+37-14-15-16-17

=(34-14)+(35-15)+(36-16)+(37-17)

=20+20+20+20

=80

khùng

a) \(A=\dfrac{3}{4}.\dfrac{8}{9}.\dfrac{15}{16}.\dfrac{24}{25}.....\dfrac{120}{121}.\dfrac{143}{144}\)

= \(\dfrac{1.3.2.4.3.5.4.6....10.12.11.13}{2^2.3^2.4^2.5^2...11^2.12^2}\)

= \(\dfrac{1.2.12.13}{2^2.12^2}=\dfrac{13}{2.12}=\dfrac{13}{24}\)

b) \(B=\dfrac{5}{9}.\dfrac{21}{25}.\dfrac{45}{49}.\dfrac{77}{81}....\dfrac{357}{361}.\dfrac{437}{441}\)

= \(\dfrac{1.5.3.7.5.9.7.11.....17.21.19.23}{3^2.5^2.7^2....19^2.21^2}=\dfrac{1.3.21.23}{3^2.21^2}\)

= \(\dfrac{23}{3.21}=\dfrac{23}{63}\)