a. 36 + (-15) + 27 + (-36) + 15

= 36 - 15 + 27 - 36 + 15

= 36 - 36 - 15 + 15 + 27

= 0 - 0 + 27

= 27

b. -12 + 34 + (-28) + 12 + (-34)

= 34 - 12 - 28 + 12 - 34

= 34 - 34 - 12 + 12 - 28

= 0 - 0 - 28

= -28

c. -15 + 16 + (-25) + 34 + (-23)

= 16 - 15 - 25 + 34 - 23

= 16 + 34 - 15 - 15 - 23

= 50 - 30 - 23

= -3

d. -12 + 8 + 18 + (-17) + 81 + (-71) + 1

= 8 - 12 + 18 - 17 + 81 - 71 + 1

= -4 + 1 + 10 + 1

= -3 + 11

= 8

e. -284 + 184 + 35 + (-25)

= 184 - 284 + 35 - 25

= -100 + 10

= -90

ơ má dinh gút chóp bn

\(a,\dfrac{1}{2}-\dfrac{1}{3}-\left(-\dfrac{5}{4}\right)=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{5}{4}=\dfrac{1\times6-1\times4+5\times3}{12}=\dfrac{6-4+15}{12}=\dfrac{17}{12}\\ b,\dfrac{5}{4}-\dfrac{1}{2}-\dfrac{7}{8}=\dfrac{5\times2-1\times4-7}{8}=\dfrac{10-4-7}{8}=-\dfrac{1}{8}\\ c,\dfrac{1}{5}-\dfrac{1}{2}+\dfrac{9}{10}=\dfrac{1\times2-1\times5+9}{10}=\dfrac{2-5+9}{10}=\dfrac{6}{10}=\dfrac{3}{5}\\ d,\dfrac{5}{4}-\dfrac{1}{3}+\dfrac{7}{6}=\dfrac{5\times3-1\times4+7\times2}{12}=\dfrac{15-4+14}{12}=\dfrac{25}{12}\)

`1/2+(-1/3)-(-5/4)`

`=1/2-1/3+5/4`

`=3/6-2/6+5/4`

`=1/6+5/4`

`=2/12+15/12`

`=17/12`

__

`5/4-1/2+(-7/8)`

`=5/4-1/2-7/8`

`=10/8-4/8-7/8`

`=6/8-7/8`

`=-1/8`

__

`1/5-1/2+9/10`

`=2/10-5/10+9/10`

`=-3/10+9/10`

`=6/10`

`=3/5`

__

`5/4-1/3+7/6`

`=15/12-4/12+14/12`

`=11/12+14/12`

`=25/12`

`#lv`

(n+12)\(⋮\)(n+1)

(n+1+11)\(⋮\)(n+1)

1+11\(⋮\)(n+1)

=>n=0,n=10

Bài toán 5:

a.

$x+(-13)=-144-(-78)$

$x-13=-144+78$

$x=-144+78+13=-144+91=-(144-91)=-53$

b.

$x+76=58-(-16)=58+16=74$

$x=74-76=-(76-74)=-2$
c.

$453+x=-44-(-199)=-44+199$

$x=-44+199-453=199-(453+44)=199-497$

$x=-(497-199)=-298$

d.

$-x+8=12$

$-x=12-8=4$

$x=-4$

e.

$x+8+8=7$

$x+16=7$

$x=7-16=-(16-7)=-9$

f.

$8x=-104+2^8=-104+256=256-104=152$

$x=152:8=19$

Bài 6:

a. Tập hợp các số nguyên x thỏa mãn là:

$\left\{-4; -3; ....;3\right\}$

Tổng:

$(-4)+(-3)+...+2+3=(-4)+[(-3)+3]+[(-2)+2]+[(-1)+1]+0$

$=-4+0+0+0+0=-4$

e.

Tập hợp các số nguyên x thỏa mãn là:

$\left\{-16; -15; -14;....;-1\right\}$

Tổng:

$(-16)+(-15)+(-14)+...+(-1)$

$=-(16+15+14+...+1)$

$=-\frac{16.17}{2}=-136$

ok bạn

Bạn ra đi 

Tìm y 

y - 105 : 21 = 15 

Giúp mik nha ! Hãy trình bày ra nhé ! Thank you

\(315+\left(125-y\right)=435\)

\(\Rightarrow125-y=435-315\)

\(\Rightarrow125-y=120\)

\(\Rightarrow y=125-10\)

\(\Rightarrow y=5\)

a) 2x + 37 = 45

=> 2x = 45 - 37 = 8

=> x = 4

b) 35 - ( 5 . ( x - 1 ) = 10

=> 5 . ( x - 1 ) = 35 - 10 = 25

=> x - 1 = 25 : 5 = 5

=> x = 6

c) 4 . 2^x - 3 = 125

=> 4 . 2^x = 128

=> 2^x = 128 : 4 = 32

=> 2^x = 2⁵

=> x = 5

d) 32 ⁝ x 

=> x ∈ Ư(32) = { 1 ; 2 ; 4 ; 8 ; 16 ; 32 }

A)2X+17=45

=>2X=28

=>X=14

B)35 - 5(X-1)=10

=>5(7-X+1)=10

=>8-X=2

=>X=6