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Giải tiêu biểu câu a nhé.
a/ \(5x\left(2x-7\right)+2x\left(8-5x\right)=5\)
\(\Leftrightarrow19x+5=0\)
\(\Leftrightarrow x=-\frac{5}{19}\)
a) ĐKXĐ: x khác +2
\(\frac{x-2}{2+x}-\frac{3}{x-2}-\frac{2\left(x-11\right)}{x^2-4}\)
<=> \(\frac{x-2}{2+x}-\frac{3}{x-2}=\frac{2\left(x-11\right)}{\left(x-2\right)\left(x+2\right)}\)
<=> (x - 2)^2 - 3(2 + x) = 2(x - 11)
<=> x^2 - 4x + 4 - 6 - 3x = 2x - 22
<=> x^2 - 7x - 2 = 2x - 22
<=> x^2 - 7x - 2 - 2x + 22 = 0
<=> x^2 - 9x + 20 = 0
<=> (x - 4)(x - 5) = 0
<=> x - 4 = 0 hoặc x - 5 = 0
<=> x = 4 hoặc x = 5
làm nốt đi
a) \(\left(\frac{x+2}{98}+1\right)+\left(\frac{x+4}{96}+1\right)=\left(\frac{x+6}{94}+1\right)+\left(\frac{x+8}{92}+1\right)\)
\(\Leftrightarrow\frac{x+100}{98}+\frac{x+100}{96}=\frac{x+100}{94}+\frac{x+100}{92}\)
\(\Leftrightarrow\left(x+100\right)\left(\frac{1}{98}+\frac{1}{96}-\frac{1}{94}-\frac{1}{92}\right)=0\)
\(\Leftrightarrow x+100=0\) ( do \(\frac{1}{98}+\frac{1}{96}-\frac{1}{94}-\frac{1}{92}\ne0\) )
\(\Leftrightarrow x=-100\)
b) \(3x^2+2x-1=0\)
\(\Leftrightarrow3x^2+3x-x-1=0\)
\(\Leftrightarrow3x\left(x+1\right)-\left(x+1\right)=0\)
\(\Leftrightarrow\left(3x-1\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}3x-1=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{1}{3}\\x=-1\end{matrix}\right.\)
a,<=>\(\frac{\left(2x+1\right)^2}{4}\)+\(\frac{2\left(2x-1\right)^2}{4}\)≥\(\frac{12\left(x+5\right)^2}{4}\)
<=>4x2+4x+1+2(4x2-4x+1)≥12(x2+10x+25)
<=>4x2+4x+1+8x2-8x+2≥12x2+120x+300
<=>4x2+4x+1+8x2-8x+2-12x2-120x-300≥0
<=>-124x-297≥0
<=>124x+297≤0
<=>124x≤-297
<=>x≤\(\frac{-297}{124}\)
b, Tương tự câu a
c, |5−3x|=2+x
TH1: 5-3x=2+x
<=> -3x - x = 2 - 5
<=> -4x = -3
<=> x = 3/4
TH2: 5-3x = -2 - x
<=> -3x + x = -2 - 5
<=> -2x = -7
<=> x = 7/2
c/ \(\frac{2x-5}{7}=\frac{5-2x}{5}\)
=> 5 (2x - 5) = 7 (5 - 2x)
=> 10x - 25 = 35 - 14x
=> 10x + 14x = 35 + 25
=> 24x = 60
=> x = 2,5
a)-4
b)6
c)5/2
\(a)\) \(\frac{8-11x}{4}=13\)
\(\Leftrightarrow\)\(8-11x=13.4\)
\(\Leftrightarrow\)\(8-11x=52\)
\(\Leftrightarrow\)\(11x=8-52\)
\(\Leftrightarrow\)\(11x=-44\)
\(\Leftrightarrow\)\(x=\frac{-44}{11}\)
\(\Leftrightarrow\)\(-4\)
Vậy \(x=-4\)
chưa ai làm câu thứ 2 sao :))
b) \(\frac{3x-4}{7}=2\)
\(\Leftrightarrow\)\(3x-4=2.7\)
\(\Leftrightarrow\)\(3x-4=14\)
\(\Leftrightarrow\)\(3x=18\Leftrightarrow x=\frac{18}{3}=6\)
Nhân chéo tích lên là được nhé
\(a\frac{8-11x}{4}=13\)
\(\Leftrightarrow8-11x=52\)
\(\Leftrightarrow-11x=44\)
\(\Leftrightarrow x=-4\)
\(b.\frac{3x-4}{7}=2\)
\(3x-4=14\)
\(\Leftrightarrow3x=18\)
\(\Leftrightarrow x=6\)
c.\(\frac{2x-5}{7}=\frac{5-2x}{5}\)
\(\Leftrightarrow5\left(2x-5\right)=7\left(5-2x\right)\)
\(\Leftrightarrow10x-25=35-14x\)
\(\Leftrightarrow10x+14x=25+35\)
\(\Leftrightarrow24x=60\)
\(\Leftrightarrow x=2,5\)
xl mik chưa kết luận nghiệm
\(a.\)vậy\(S=\left\{-4\right\}\)
B.Vậy \(S=\left\{6\right\}\)
c.vậy \(S=\left\{2,5\right\}\)