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九年级数学解答题一般
题目
(1)(1)解不等式组{5x32(x3)x4x+13\left\{\begin{array}{l}5x-3≤2(x-3)\\ \frac{x}{4}<\frac{x+1}{3}\end{array}\right.
(2)(2)解方程:1xx2=x2x41\frac{1-x}{x-2}=\frac{x}{2x-4}-1.
知识点:解二元一次方程组——代入消元法、在数轴上表示不等式的解集、解一元一次不等式组、解二元一次方程组章节:未标注

答案与解析

答案

(1){5x32(x3)x4x+13\left\{\begin{array}{l}{5x-3≤2(x-3)①}\\{\frac{x}{4}<\frac{x+1}{3}②}\end{array}\right.
解不等式①得:x1x\leqslant -1
解不等式②得:x>4x \gt -4
\therefore原不等式组的解集为:4<x1-4 \lt x\leqslant -1
(2)1xx2=x2x41(2)\frac{1-x}{x-2}=\frac{x}{2x-4}-1
2(1x)=x2(x2)2\left(1-x\right)=x-2\left(x-2\right)
解得:x=2x=-2
检验:当x=2x=-2时,2(x2)02\left(x-2\right)\neq 0
x=2\therefore x=-2是原方程的根.

解析

(1){5x32(x3)x4x+13\left\{\begin{array}{l}{5x-3≤2(x-3)①}\\{\frac{x}{4}<\frac{x+1}{3}②}\end{array}\right.
解不等式①得:x1x\leqslant -1
解不等式②得:x>4x \gt -4
\therefore原不等式组的解集为:4<x1-4 \lt x\leqslant -1
(2)1xx2=x2x41(2)\frac{1-x}{x-2}=\frac{x}{2x-4}-1
2(1x)=x2(x2)2\left(1-x\right)=x-2\left(x-2\right)
解得:x=2x=-2
检验:当x=2x=-2时,2(x2)02\left(x-2\right)\neq 0
x=2\therefore x=-2是原方程的根.

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