Bài tập theo tuần Toán 8 - Tuần 34

Đáp án D

Đáp án D

Đáp án C

Đáp án A

Đáp án D

Đáp an B

Đáp án A

Đáp án B

Đáp án A

Đáp án D

$\begin{array}{l}\frac{3x+2}{x}=\frac{2x-2}{3}\left(x\ne 0\right)\\ \Rightarrow 9x+6=2x^2-2x\\ \iff 2x^2-11x-6=0\\ \iff 2x^2+x-12x-6=0\\ \iff x\left(2x+1\right)-6(2x+1)=0\\ \iff \left(x-6\right)\left(2x+1\right)=0\\ \iff \left[\begin{array}{l}x=6(t/m)\\ x=-\frac{1}{2}(t/m)\end{array}\right.\\ S=\left\{6;\frac{-1}{2}\right\}\end{array}$

$\begin{array}{l}\\ \iff x^2-5x=x^2+4x+4+5\\ \iff -5x-4x=4+5\\ \iff -9x=9\\ \iff x=-1\\ S=\left\{-1\right\}\end{array}$

$\begin{array}{l}\frac{x+2}{x-2}-\frac{1}{x}=\frac{2}{x(x-2)}\left(\begin{array}{l}x\ne 0\\ x\ne 2\end{array}\right)\\ \iff \frac{x(x+2)-(x-2)}{x(x-2)}=\frac{2}{x(x-2)}\\ \Rightarrow x^2+2x-x+2=2\\ \iff x^2+x=0\iff x\left(x+1\right)=0\\ \iff \left[\begin{array}{l}x=0\left(loai\right)\\ x=-1(t/m)\end{array}\right.\\ S=\left\{-1\right\}\end{array}$

$\begin{array}{l}1)\frac{x-3}{5}\ge 2x-6\iff \frac{x-3}{5}-\frac{10x}{5}+\frac{30}{5}\ge 0\\ \iff -9x+27\ge 0\iff 9x\le 27\iff x\le 3\\ S=\left\{x/x\le 3\right\}\end{array}$