Cho x thuoc { -21; -20; -19; -18; -17} va y thuoc { -3; -4; ...; -13; -14}
a) Co bao nhieu gia tri x+y khac nhau ?
b) Hay xac dinh gia tri be nhat va gia tri lon nhat cua x+y.
cho a,b thuoc Z.Tim x thuoc Z sao cho:
x-a=2
x+b=4
a-x=21
14-x=b+9
có câu trả lời ở olm củaNCTK đó
gõ vào phần tìm kiếm câu hỏi, chủ đề là ra
cho a,b thuoc Z.Tim x thuoc Z sao cho
a, x-a=2 b, x+b=4
c, a-x=21 d, 14-x=b+9
tim cac so tu nhien x , biet :
a, x thuoc U(18) va x thuoc B(4)
b, x thuoc U(36) va x > hoac = 12
c, x thuoc B(12) VA 30 < HOAC = X < HOAC = 100
d, x thuoc U(28) va x thuoc U (21)
a: \(x\in\left\{1;2;3;6;9;18\right\}\)
mà \(x\in B\left(4\right)\)
nên \(x\in\varnothing\)
b: \(x\in\left\{1;2;3;4;6;9;12;18;36\right\}\)
mà x>=12
nên \(x\in\left\{12;18;36\right\}\)
c: \(x\in\left\{0;12;24;36;48;60;72;84;96;108;...\right\}\)
mà 30<=x<=100
nên \(x\in\left\{36;48;60;72;84;96\right\}\)
d: \(x\inƯC\left(28;21\right)\)
\(\Leftrightarrow x\inƯ\left(7\right)\)
hay \(x\in\left\{1;7\right\}\)
tim x biet
X thuoc boi (25) va x <- 100
x thuoc uoc (30) va x >10
x chia het cho 21 va x< 60
45 chia het cho xva x <-9
\(B\left(25\right)=\left\{0;25;50;75;100;125;...\right\}\)
\(x\le100\Rightarrow x\in\left\{0;25;50;75;100\right\}\)
Vậy \(x\in\left\{0;25;50;75;100\right\}\).
\(Ư\left(30\right)=\left\{1;2;3;5;6;10;15;30\right\}\)
\(x>10\Rightarrow x\in\left\{15;30\right\}\)
Vậy \(x\in\left\{15;30\right\}\).
\(x⋮21\Rightarrow x\in B\left(21\right)=\left\{0;21;42;63;...\right\}\)
Mà \(x< 60\) nên \(x\in\left\{0;21;42\right\}\)
Vậy \(x\in\left\{0;21;42\right\}\).
\(45⋮x\Rightarrow x\inƯ\left(45\right)=\left\{1;3;5;9;15;45\right\}\)
Mà \(x\le9\) nên \(x\in\left\{1;3;5;9\right\}\)
Vậy \(x\in\left\{1;3;5;9\right\}\).
tim STN x biet
a, 21 thuoc B(x-3)
b, 1-x thuoc U(17)
c, 2x+3 thuoc B(2x-1)
d, x+1 thuoc U(x mu 2+x+3)
e, 3x+1:11-2x
a: \(\Leftrightarrow x-3\inƯ\left(21\right)\)
\(\Leftrightarrow x-3\in\left\{-3;-1;1;3;7;21\right\}\)
hay \(x\in\left\{0;2;4;6;10;24\right\}\)
b: \(\Leftrightarrow x-1\in\left\{1;-1;17\right\}\)
hay \(x\in\left\{2;0;18\right\}\)
c: \(\Leftrightarrow2x-1+4⋮2x-1\)
\(\Leftrightarrow2x-1\in\left\{1;-1\right\}\)
hay \(x\in\left\{1;0\right\}\)
d: \(\Leftrightarrow x^2+x+3⋮x+1\)
\(\Leftrightarrow x+1\inƯ\left(3\right)\)
\(\Leftrightarrow x+1\in\left\{1;3\right\}\)
hay \(x\in\left\{0;2\right\}\)
cho x= 2^10+2^11+2^12+...+2^20+2^21/7 chung to x thuoc N sao
Ta có:7x=210+211+...............+221
7x=(210+211+212)+(213+214+215)+...........+(219+220+221)
7x=210.(1+2+22)+213.(1+2+22)+............+219.(1+2+22)
7x=(210+213+216+219).(1+2+22)=(210+213+216+219).7
\(\Rightarrow x=2^{10}+2^{13}+2^{16}+2^{19}\in N\)*
21 thuoc B(x-3). tìm x
Cho tong A= 12+15+21+x voi x thuoc N. Tim dieu kien cua x de A chia het cho 3, A ko chia het cho 3
Vay bang bao nhieu the bn ? co ai b ko ?
tim x thuoc N
(7.13+8.13):(8+21-x)=39
(7.13+8.13):(8+21-x)=39
13(7+8):(29-x)=39
13.15:(29-x)=39
195:(29-x)=39
29-x=195:39
29-x=5
x=5+29
x=34
PT tương đương với:
\(\Leftrightarrow13\cdot\left(7+8\right):\left(29-x\right)=3\cdot13\)
\(\Leftrightarrow15:\left(29-x\right)=3\)
\(\Leftrightarrow29-x=15:3=5\)
\(\Leftrightarrow x=29-5=24.\)