1/

a/ |a| < 5 => a \(\in\){-4;-3;-2;-1;0;1;2;3;4}

b/ |a| = a => a\(\inℤ\)

c/ 4<|a| => a \(\in\){...;-8;-7;-6;-5;5;6;7;8;...}

2/a/ |-4| + |2| + |-19| + |-16| = \(4+2+19+16\)= 41

b/ |-16| + |-19| - |-4| - |-2| =\(16+19-4-2\)= 39

c/|92| + |26| + |110| + |-329| =\(92+26+110+329\)=36308

Xin lỗi nha. Câu 1b bị sai r

|a|=a

=> a\(\in\)\(ℕ\)

a) Sửa đề CMR : \(\left(\frac{a+b+c}{b+c+d}\right)^3=\frac{a}{d}\) 

\(\frac{a}{b}=\frac{b}{c}=\frac{c}{d}=\frac{a+b+c}{b+c+d}\)

=> \(\left(\frac{a}{b}\right)^3=\left(\frac{b}{c}\right)^3=\left(\frac{c}{d}\right)^3=\left(\frac{a+b+c}{b+c+d}\right)^3\)

=> \(\left(\frac{a}{b}\right)^3=\left(\frac{a+b+c}{b+c+d}\right)^3\)

=> \(\frac{a}{b}.\frac{a}{b}.\frac{a}{b}=\left(\frac{a+b+c}{b+c+d}\right)^3\)

=> \(\frac{a}{b}.\frac{b}{c}.\frac{c}{d}=\left(\frac{a+b+c}{b+c+d}\right)^3\left(\text{vì }\frac{a}{b}=\frac{b}{c}=\frac{c}{d}\right)\)

=> \(\frac{a}{d}=\left(\frac{a+b+c}{b+c+d}\right)^3\left(\text{đpcm}\right)\)

b) |17x - 5| - |17x + 5| = 0

=> |17x - 5| = |17x + 5|

=> \(\orbr{\begin{cases}17x-5=17x+5\\17x-5=-17x-5\end{cases}}\Rightarrow\orbr{\begin{cases}0x=10\\34x=0\end{cases}}\Rightarrow\orbr{\begin{cases}x\in\varnothing\\x=0\end{cases}}\Rightarrow x=0\)

Vậy x = 0 là giá trị cần tìm

Ta có a+b+c-(a+b-2c)=-2-(-8)

<=>3c=6

=>c=2

=>a+b=-4; a-2b=-1

=>a+b-(a-2b)=-4-(-1)

<=>3b=-3

=>b=-1

=>a=-3

TA có (A+B+C)+(A-B-C)=2A

              110   +     2    =112

=>2A=112

=>A=56

=>B+C=110-56=54

Vì B-15=C+15

=>B+C=15+15=30

=>B=(54+30):2=42

=>C=54-42=12

Vậy A=56;B=42;C=12

Bài 2: Mình nghĩ câu a là a+2b-3c=-20

a) Ta có: a/2 = b/3 = c/4 = 2b/6 = 3c/12 = a + 2b - 3c/ 2 + 6 - 12 = -20/-4 = 5

a/2 = 5 => a = 2 . 5 = 10

b/3 = 5 => b = 5 . 3 = 15

c/4 = 5 => c = 5 . 4 = 20

Vậy a = 10; b = 15; c = 20

b) Ta có: a/2 = b/3 => a/10 = b/15

              b/5 = c/4 => b/15 = c/12

=> a/10 = b/15 = c/12 = a - b + c / 10 - 15 + 12 = -49/7 = -7

a/10 = -7 => a = -7 . 10 = -70

b/15 = -7 => b = -7 . 15 = -105

c/12 = -7 => c = -7 . 12 = -84

Vậy a = -70; b = -105; c = -84.

bài 1

a:b:c:d=2:3:4:5=

Bài 1:

Ta có: a:b:c:d = 2:3:4:5

=> a/2 = b/3 = c/4 = d/5 = a+b+c+d/2+3+4+5 = -42/14 = -3

a/2 = -3 => a = -3 . 2 = -6

b/3 = -3 => b = -3 . 3 = -9

c/4 = -3 => c = -3 . 4 = -12

d/5 = -3 => d = -3 . 5 = -15

Vậy a = -6; b = -9; c = -12; d = -15.

A

\(\text{A.}1\)

1

rồi mình k cho

giúp mình với

c là:

1-3=-2

d là:

1-4=-3

b là:

1-2=-1

a là:

1-(-1+-3+-2)=7

k cho mk nha

TL:

a+b+c+d = 1

=> b= 1-  (a+c+d)= 1-2 =-1

=> c= 1 - (a+b+d) = 1- 3 = -2

=> d = 1- (a+b+c) = 1-4 =-3

=> a = 1 - ( -1) - (-2) - (-3) = 7

Học tốt

\(\hept{\begin{cases}a+b+c+d=1\\a+c+d=2\end{cases}}\Leftrightarrow b=-1\)

\(\hept{\begin{cases}a+b+c+d=1\\a+b+d=3\end{cases}}\Leftrightarrow c=-2\)

\(a+b+c=4\Leftrightarrow a=7\)

\(\Rightarrow d=-3\)