
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.



xem ai thông minh, tinh mắt nhất có thể luận ra toàn bộ đề và giúp mk giải nào!!

Ta có: \(\dfrac{1}{2}\cdot y+\dfrac{2}{3}\cdot y=\dfrac{7}{6}\Rightarrow y\left(\dfrac{1}{2}+\dfrac{2}{3}\right)=\dfrac{7}{6}\Rightarrow\dfrac{7}{6}y=\dfrac{7}{6}\Rightarrow y=\dfrac{7}{6}:\dfrac{7}{6}=1\)
Vậy \(D=\left\{1\right\}\)


b)Đặt \(\frac{2x}{3}=\frac{3y}{4}=\frac{4z}{5}=k\)
\(\Rightarrow x=\frac{3k}{2}\)
\(y=\frac{4k}{3}\)
\(z=\frac{5k}{4}\)
\(x+y+z=98\)
\(\Leftrightarrow\frac{3k}{2}+\frac{4k}{3}+\frac{5k}{4}=98\)
\(\frac{18k}{12}+\frac{16k}{12}+\frac{15k}{12}=98\)
\(\frac{18k+16k+15k}{12}=98\)
\(49k=1176\)
\(k=24\)
\(\Rightarrow x=\frac{3k}{2}=\frac{3\cdot24}{2}=\frac{72}{2}=36\)
\(y=\frac{4k}{3}=\frac{4\cdot24}{3}=\frac{96}{3}=32\)
\(z=\frac{5k}{4}=\frac{5\cdot24}{4}=\frac{120}{4}=30\)
Vậy ... (kết luận tự túc)

\(\Rightarrow\dfrac{5}{4}-\dfrac{1}{4}x=\dfrac{3}{10}x-\dfrac{2}{5}\)
\(\Rightarrow\dfrac{5}{4}+\dfrac{2}{5}=\dfrac{3}{10}x-\dfrac{1}{4}x\)
\(\Rightarrow\dfrac{33}{20}=\dfrac{11}{20}x\)
\(\Rightarrow x=\dfrac{33}{20}\div\dfrac{11}{20}\)
\(\Rightarrow x=3\)
\(1\dfrac{1}{4}-x\dfrac{1}{4}=x\cdot30\%\cdot\dfrac{2}{5}\)
\(\Leftrightarrow\dfrac{5}{4}-x\dfrac{1}{4}=x\cdot\dfrac{3}{10}-\dfrac{2}{5}\)
\(\Leftrightarrow\dfrac{5}{4}-\dfrac{1}{4}x=\dfrac{3}{10}x-\dfrac{2}{5}\)
\(\Leftrightarrow25-5x=6x-8\)
\(\Leftrightarrow-5x-6x=-8-25\)
\(\Leftrightarrow-11x=-33\)
\(\Leftrightarrow x=3\)
Vậy x = 3


Bài 1
a) A : { 12;13;14 }
b) B : { 1;2;3;4;5 }
c) C : { 17;18;19;20;21 }
d) D : { 7;8;9;10 }
Bài 2
a) M : { 0;1;2;3;4;5;6 }
M : { x thuộc N / x < 7 }
b) P : { 22;23;24;25 }
P : { x thuộc N / 21 < x < 26 }
4:
a: OA<OB
=>A nằm giữa O và B
b: A nằm giữa O và B
=>OA+AB=OB
=>AB=4cm
c: OH=HA=OA/2=1,5cm
HB=7-1,5=5,5cm
2:
a: -3/5-x=1/2
=>x=-3/5-1/2=-6/10-5/10=-11/10
b: 3x-5/6=-14/21:2/7=-2/3*7/2=-7/3
=>3x=-7/3+5/6=-14/6+5/6=-9/6=-3/2
=>x=-1/2
c: 1/3(3x-2)+1/4=-9/6=-3/2
=>1/3(3x-2)=-3/2-1/4=-7/4
=>x-2/3=-7/4
=>x=-13/12