Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(a)\frac{x}{8}=\frac{-30}{y}=\frac{-48}{32}\)
Rút gọn : \(\frac{-48}{32}=\frac{(-48):16}{32:16}=\frac{-3}{2}\)
* Ta có : \(\frac{x}{8}=\frac{-3}{2}\)
\(\Rightarrow x\cdot2=-3\cdot8\)
\(\Rightarrow x=\frac{-3\cdot8}{2}=-12\)
* Ta có : \(\frac{-30}{y}=\frac{-3}{2}\)
\(\Rightarrow-30\cdot2=-3\cdot y\)
\(\Rightarrow y=\frac{-30\cdot2}{-3}=20\)
Mấy bài kia làm tương tự
\(\left(3x-1\right)⋮\left(x+1\right)\)
\(\Rightarrow\left(3x+3-4\right)⋮\left(x+1\right)\)
\(\Rightarrow\left(-4\right)⋮\left(x+1\right)\)
\(\Rightarrow x+1\inƯ\left(-4\right)=\left\{-4;-1;1;4\right\}\)
\(\Rightarrow x\in\left\{-5;-2;0;3\right\}\)
Bài 1
a) \(\frac{5}{6}=\frac{x-1}{x}\)
<=> 5x=6x-6
<=> 5x-6x=-6
<=> -11x=-6
<=> \(x=\frac{6}{11}\)
b)c)d) nhân chéo làm tương tự
\(a)\frac{x}{4}=\frac{-15}{y}=\frac{z}{52}=\frac{-32}{64}\)
Rút gọn phân số : \(\frac{-32}{64}=\frac{-32:32}{64:32}=\frac{-1}{2}\)
* Ta có : \(\frac{x}{4}=\frac{-1}{2}\)
\(\Rightarrow2x=-4\)
\(\Rightarrow x=(-4):2=-2\)
* Ta có : \(\frac{-15}{y}=\frac{-1}{2}\)
\(\Rightarrow(-1)\cdot y=-30\)
\(\Rightarrow-y=-30\)
\(\Rightarrow y=30\)
* Ta có : \(\frac{z}{52}=\frac{-1}{2}\)
\(\Rightarrow2z=(-1)\cdot52\)
\(\Rightarrow2z=-52\)
\(\Rightarrow z=-26\)
b, Tương tự câu a
a, ta có \(\frac{x}{4}\)= \(\frac{-32}{64}\)=> \(\frac{x}{4}\)= \(\frac{-1}{2}\)=> x = -2
\(\frac{-15}{y}\) = \(\frac{-32}{64}\) => \(\frac{-15}{y}\) = \(\frac{-1}{2}\) => y = 30
\(\frac{z}{52}\) = \(\frac{-32}{64}\) => \(\frac{z}{52}\) = \(\frac{-1}{2}\) => z = -26
vậy x = -2 ; y = 30 ; z = -26
câu b làm tương tự câu a
\(a,\frac{3}{4}.\left(x+2\right)+\frac{1}{2}.\left(x-\frac{1}{2}\right)=\frac{15}{4}\)
\(\frac{3}{4}.x+\frac{3}{4}.2+\frac{1}{2}.x+\frac{1}{2}.\left(-\frac{1}{2}\right)=\frac{15}{4}\)
\(\left(\frac{3}{4}.x+\frac{1}{2}.x\right)+\frac{3}{2}-\frac{1}{4}=\frac{15}{4}\)
\(\left(\frac{3}{4}+\frac{1}{3}\right).x=\frac{15}{4}+\frac{1}{4}-\frac{3}{2}\)
\(\frac{5}{4}.x=\frac{5}{2}\)
\(x=\frac{5}{2}:\frac{5}{4}\)
\(x=2\)
\(b,3.x-\frac{3}{5}=0\)
\(3.x=0+\frac{3}{5}\)
\(3.x=\frac{3}{5}\)
\(x=\frac{3}{5}:3\)
\(x=\frac{1}{5}\)
\(c,\frac{-2}{3}.x-\frac{1}{3}.\left(2.x-3\right)=\frac{3}{2}\)
\(\frac{-2}{3}.x-\frac{2}{3}.x+1=\frac{3}{2}\)
\(\left(\frac{-2}{3}-\frac{2}{3}\right).x=\frac{3}{2}-1\)
\(-\frac{4}{3}.x=\frac{1}{2}\)
\(x=\frac{1}{2}:\left(\frac{-4}{3}\right)\)
\(x=\frac{-3}{8}\)
Học tốt
Đáp án cần chọn là: D