X=(1800+600):30):560:(315:35)

X=(2400:30):560:9

X=80:560:9

X=80x1/560x1/9

X=1/7x1/9

X=1/63

A=58x72+63x81-58x52-63x61

  = (58x72-58x52)+(63x81-63x61)

  = 58(72-52)+63(81-61)

  = 58x20+63x20

  = 1160+1260

  = 2420

B=87x96-27x13+13x27-87x86

  = (87x96-87x86)-(27x13-13x27)

  = 87(96-86)-27(13-13)

  = 87x10 - 27x0

  = 870-0

  = 870

C= 53x39+87x39-53x31-47-21

  = (53x39+87x39)-(53x31+47+21)

  = 39(53+87)-(53x31+68)

  = 39x140 - 53x31 -68

  = 5460 - 1643 - 68

  = 3749

1) \(\cot51^0=\tan39^0\)

\(\cot79^015'=\tan10^045'\)

Do đó: \(\cot79^015'< \tan13^0< \tan28^0< \cot51^0< \tan47^0\)

2) \(\cos62^0=\sin28^0\)

\(\cos63^041'=\sin26^019'\)

\(\cos87^0=\sin3^0\)

Do đó: \(\cos87^0< \cos63^041'< \cos62^0< \sin47^0< \sin50^0\)

Bài 2:

a. $=62-81-12+59-9=(62-12)+(59-9)-81$

$=50+50-81=100-81=19$

b. $=39+13-26-62-39=(39-39)+13-(26+62)$

$=0+13-88=-(88-13)=-75$

c. $=(32-42)+(36-34)+(40-38)=10+2+2=14$
d. $=92-55+8-45=(92+8)-(55+45)=100-100=0$

Bài 1:

a. $=(387-87)-224=300-224=76$

b. $=-(75+35)+379=-110+379=379-110=269$

c. $=(11+15)-(13+17)=25-30=-5$

d. $=(31-21)-(27-24)=10-3=7$

-1735,k

a)  -374

b)  -1800

Bài 2:

a: \(387+\left(-224\right)+\left(-87\right)\)

\(=\left(387-87\right)+\left(-224\right)\)

=300-224

=76

b: \(39+\left(13-26\right)-\left(62+39\right)\)

\(=39+13-26-62-39\)

\(=\left(39-39\right)+\left(13-26-62\right)\)

=0-75

=-75

c: \(32-34+36-38+40-42\)

\(=\left(32-34\right)+\left(36-38\right)+\left(40-42\right)\)

\(=\left(-2\right)+\left(-2\right)+\left(-2\right)\)

=-6

d: \(92-\left(55-8\right)+\left(-45\right)\)

\(=92-55+8-45\)

\(=\left(92+8\right)-\left(55+45\right)\)

=100-100

=0

e: -20<=x<=20

mà x nguyên

nên \(x\in\left\{-20;-19;-18;...;18;19;20\right\}\)

=>M={-20;-19;-18;-17;...;18;19;20}

Tổng các phần tử của M là:

\(\left(-20\right)+\left(-19\right)+\left(-18\right)+\left(-17\right)+...+18+19+20\)

\(=\left(-20+20\right)+\left(-19+19\right)+...+\left(-2+2\right)+\left(-1+1\right)+0\)

=0+0+...+0

=0

( 13 * 78 + 13 * 22 ) + ( 87 * 55 + 87 * 45 )

= 13 * ( 78 + 22 ) + 87 * ( 55 + 45 )

= 13 *    100   +    87 *   100

= 1300   + 8700

=      10 000

trả lời nhanh giúp tớ với đang cần gấp

-1300

-3600

1544

13.(-87)+(-13).13= 13.(-87+(-13))

                        = 13.(-100)

                        =-1300

13.(-87)+(-13).13

=13.[(-87)+(-13)]

=13.(-100)

=-1300

36.(-54)+92.(-18)

=36.(-54)+36.2.(-18)

=36.(-54)+36.(-36)

=36.[(-54)+(-36)]

=36.(-100)

=-3600