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\(3\left(x-1\right)+4=28\)
\(\Rightarrow3x-3=28-4\)
\(\Rightarrow3x-3=24\)
\(\Rightarrow3x=24+3\)
\(\Rightarrow3x=27\)
\(\Rightarrow x=27\div3\)
\(\Rightarrow x=9\)
a,x- 2/3= -1/2
x= -1/2 + 2/3
x= 1/6
b,20%.x - x +1/5 =3/4
1/5.x - x +1/5 = 3/4
1/5.x-x =3/4 - 1/5
x.(1/5 - 1)=11/20
x.-4/5 =11/20
x=11/20 : -4/5=-11/16
a) \(x-\frac{2}{3}=-\frac{1}{2}\)
\(\Leftrightarrow x=\frac{2}{3}-\frac{1}{2}\)
\(\Leftrightarrow x=\frac{1}{6}\)
b) \(20\%x-x+\frac{1}{5}=\frac{3}{4}\)
\(\Leftrightarrow\frac{1}{5}x-x=\frac{3}{4}-\frac{1}{5}\)
\(\Leftrightarrow-\frac{4}{5}x=\frac{11}{5}\)
\(\Leftrightarrow x=\frac{11}{5}:\left(-\frac{4}{5}\right)\)
\(\Leftrightarrow x=-\frac{11}{4}\)
1) 5.(3-x)+2.(x-7)=-14
15-5x+2x-14=-14
1-3x=-14
3x=15
X=5
2) 30.(x+2)-6.(x-5)-24x=100
30x+60-6x+30-24x=100
0X+90=100
0X=10 vô lí
=> ko có giá trị x thỏa mãn điều kiện
3) (3x-9)^2=36
3x-9=6
3x-9=-6
TH1:3x-9=6 TH2:3x-9=-6
3x=15 3x=3
X=5 x=1
Vậy….
4) (1-2x)^3=-27
(1-2x)3=(-3)3
1-2x=-3
2x=4
X=2
Vậy…
5) (x-3).(x-2)<0
=>x-3 và x-2 cùng dấu
TH1:x-3>0 TH2:x-3<0
x-2<0 x-2>0
=>X>3 =>x<3
X<2 x>2
=>x>3 =>x<2
Vậy 3<x<2
câu 6 chịuuuu
câu 5 hơi khó ko bt có đúng hay ko đâu :)))
3) \(\left(3x-9\right)^2=36\Leftrightarrow\orbr{\begin{cases}3x-9=6\\3x-9=-6\end{cases}\Leftrightarrow\orbr{\begin{cases}3x=15\\3x=3\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=5\\x=1\end{cases}}}\)
4) \(\left(1-2x\right)^3=-27\)
<=> 1-2x=-3
<=> 3x=4
<=> \(x=\frac{4}{3}\)
5) (x-3)(x-2)<0
=> x-3 và x-2 trái dấu nhau
thấy x-3<x-2 => \(\hept{\begin{cases}x-3< 0\\x-2>0\end{cases}\Leftrightarrow\hept{\begin{cases}x< 3\\x>2\end{cases}\Leftrightarrow}2< x< 3}\)
6) làm tương tự
a, x-1:4/3+9/16=-5^(^laf mũ)2/4^2
x-1:4/3+9/16=25/16
x-1:4/3=25/16-9/16
x-1:4/3=1
x-1=1.4/3
x-1=4/3
x=4/3+1
x=7/3
kl:...................(hì tự viết nha mik lười viết)
b, 5/2x+2-31/2=1/6
5/2x+2=1/6+31/2
5/2x+2=16
5/2x=16-2
5/2x=14
x=14:5/2
x=28/5(vì 28 ko chia hết cho 5 nên mik viết như vậy)
*chúc bn học tốt nha* ^-^ *_*
Với tất cả các câu, mk chỉ làm ngắn gọn. Nếu bn muốn đầy đủ, thì bn tự lập bảng rồi xét.
1. \(13⋮\left(x-3\right)\)
\(\Leftrightarrow\left(x-3\right)\inƯ\left(13\right)=\left\{\pm1;\pm13\right\}\)
\(\Rightarrow x\in\left\{2;4;-10;16\right\}\)
Vậy x = ......................
2. \(\left(x+13\right)⋮\left(x-4\right)\)
\(\Leftrightarrow\left(x-4\right)+17⋮\left(x-4\right)\)
\(\Leftrightarrow17⋮x-4\)
\(\Leftrightarrow\left(x-4\right)\inƯ\left(17\right)=\left\{\pm1;\pm17\right\}\)
\(\Rightarrow x\in\left\{3;5;-13;21\right\}\)
Vậy x = ...................
3. \(\left(2x+108\right)⋮\left(2x+3\right)\)
\(\Leftrightarrow\left(2x+3\right)+105⋮\left(2x+3\right)\)
\(\Leftrightarrow105⋮\left(2x+3\right)\)
\(\Leftrightarrow\left(2x+3\right)\inƯ\left(105\right)\)\(=\left\{\pm1;\pm3;\pm5;\pm7;\pm15;\pm21;\pm35;\pm105\right\}\)
\(\Rightarrow x=-2;-1;-3;0;-4;1;-5;2;...............\)
4. \(17x⋮15\)
\(\Leftrightarrow x⋮15\) ( vì \(\left(15,17\right)=1\) )
Do đó : Với mọi x thuộc Z thì \(17x⋮15\)
6. \(\left(x+16\right)⋮\left(x+1\right)\)
\(\Leftrightarrow\left(x+1\right)+15⋮\left(x+1\right)\)
\(\Leftrightarrow15⋮\left(x+1\right)\)
\(\Leftrightarrow\left(x+1\right)\inƯ\left(15\right)=\left\{\pm1;\pm3;\pm5;\pm15\right\}\)
\(\Rightarrow x\in\left\{-2;0;-4;2;-6;4;-16;14\right\}\)
Vậy x = .....................
7. \(x⋮\left(2x-1\right)\)
Mà \(\left(2x-1\right)\) lẻ
Nên : Với mọi x thuộc Z là số lẻ thì \(x⋮\left(2x-1\right)\)
8. \(\left(2x+3\right)⋮\left(x+5\right)\)
\(\Leftrightarrow\left(2x+10\right)-7⋮\left(x+5\right)\)
\(\Leftrightarrow2.\left(x+5\right)-7⋮\left(x+5\right)\)
\(\Leftrightarrow7⋮\left(x+5\right)\)
\(\Leftrightarrow\left(x+5\right)\inƯ\left(7\right)=\left\{\pm1;\pm7\right\}\)
\(\Rightarrow x\in\left\{-6;-4;-12;2\right\}\)
Vậy x = .........................
\(\left(50\%x+\frac{9}{4}\right):\frac{-2}{3}=\frac{17}{6}\)
\(\left(\frac{1}{2}x+\frac{9}{4}\right):\frac{-2}{3}=\frac{17}{6}\)
\(\frac{1}{2}x+\frac{9}{4}=\frac{17}{6}.\frac{-2}{3}\)
\(\frac{1}{2}x+\frac{9}{4}=\frac{-17}{9}\)
\(\frac{1}{2}x=\frac{-17}{9}-\frac{9}{4}\)
\(\frac{1}{2}x=\frac{-149}{36}\)
\(x=\frac{-149}{36}:\frac{1}{2}\)
\(x=\frac{-149}{18}\)
~ Hok tốt ~
a) Bấm máy là ra (mình chỉ giải câu b)
b) (50%x+ 9/4) : -2/3=17/6
<=> (1/2x + 9/4) = 17/9
<=> 1/2x= 17/9 - 9/4
<=> 1/2x = -13/36
<=> x= -13/72
\(a)\left(3\frac{1}{2}-x\right).1\frac{1}{4}=\frac{15}{6}\)
\(\left(\frac{7}{2}-x\right).\frac{5}{4}=\frac{15}{6}\)
\(\frac{7}{2}-x=\frac{15}{6}:\frac{5}{4}\)
\(\frac{7}{2}-x=2\)
\(x=\frac{7}{2}-2\)
\(\Rightarrow x=\frac{3}{2}\)
a) \(-\frac{7}{2}:\left(3-x\right)-0,75=\frac{1}{4}\)
\(\Leftrightarrow\frac{-7}{2\left(3-x\right)}=\frac{1}{4}+0,75=0,25+0,75=1\)
\(\Leftrightarrow2\left(3-x\right)=-7\)
\(\Leftrightarrow3-x=-\frac{7}{2}\)
\(\Leftrightarrow x=3+\frac{7}{2}\)
\(\Leftrightarrow x=\frac{13}{2}\)
b) \(\left|2x-\frac{4}{3}\right|-1\frac{1}{3}=-\frac{8}{9}\)
\(\Leftrightarrow\left|2x-\frac{4}{3}\right|=\frac{4}{3}-\frac{8}{9}=\frac{4}{9}\)
\(\Leftrightarrow\orbr{\begin{cases}2x-\frac{4}{3}=\frac{4}{9}\\2x-\frac{4}{3}=-\frac{4}{9}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}2x=\frac{4}{3}+\frac{4}{9}=\frac{16}{9}\\2x=\frac{4}{3}-\frac{4}{9}=\frac{8}{9}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=\frac{8}{9}\\x=\frac{4}{9}\end{cases}}\)