2) 2x(3x + 7) – 15x – 35 = 0
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\(\Leftrightarrow4x^2-12x-4x^2+9=-3\)
=>-12x=-12
hay x=1
\(4x\left(x-3\right)-\left(2x+3\right)\left(2x-3\right)=-3\)
\(4x^2-12x-4x^2+9+3=0\)
\(12-12x=0\\ \Rightarrow1-x=0\\ \Rightarrow x=1\)
\(a,\left(x-2\right)^2-x\left(x+2\right)=20\\ \Leftrightarrow x^2-4x+4-x^2-2x=20\\ \Leftrightarrow-6x+4=20\\ \Leftrightarrow-6x=16\\ \Leftrightarrow x=-\dfrac{8}{3}\)
\(\Leftrightarrow x^2-4x+4-x^2-2x=20\)
=>-6x=16
hay x=-8/3
b: Ta có: \(\left(4x^4-3x^3\right):\left(-x^3\right)+\left(15x^2+6x\right):3x=0\)
\(\Leftrightarrow-4x+3+5x+2=0\)
\(\Leftrightarrow x=-5\)
\(\left(x+2\right)-2=0\)
\(\Rightarrow x+2-2=0\)
\(\Rightarrow x=0\)
\(\left(x+3\right)+1=7\)
\(\Rightarrow x+3+1=7\)
\(\Rightarrow x+4=7\)
\(\Rightarrow x=3\)
\(\left(3x-4\right)+4=12\)
\(\Rightarrow3x-4+4=12\)
\(\Rightarrow3x=12\)
\(\Rightarrow x=4\)
\(\left(5x+4\right)-1=13\)
\(\Rightarrow5x+4-1=13\)
\(\Rightarrow5x+3=13\)
\(\Rightarrow5x=10\)
\(\Rightarrow x=2\)
\(\left(4x-8\right)-3=5\)
\(\Rightarrow4x-8-3=5\)
\(\Rightarrow4x-11=5\)
\(\Rightarrow4x=16\)
\(\Rightarrow x=4\)
\(8-\left(2x+4\right)=2\)
\(\Rightarrow8-2x-4=2\)
\(\Rightarrow4-2x=2\)
\(\Rightarrow2x=2\)
\(\Rightarrow x=1\)
\(7+\left(5x+2\right)=14\)
\(\Rightarrow7+5x+2=14\)
\(\Rightarrow9+5x=14\)
\(\Rightarrow5x=5\)
\(\Rightarrow x=1\)
\(5-\left(3x-11\right)=1\)
\(\Rightarrow5-3x+11=1\)
\(\Rightarrow16-3x=1\)
\(\Rightarrow3x=15\)
\(\Rightarrow x=5\)
\(\Leftrightarrow x^2-12x+36-x^2+10x=40\)
=>-2x=4
hay x=-2
\(45:\frac{2}{\frac{4}{7}}-1,25=45:\left(2.\frac{7}{4}\right)-1,25=45:\frac{7}{2}-\frac{5}{4}=45.\frac{2}{7}-\frac{5}{4}=\frac{90}{7}-\frac{5}{4}=\frac{325}{28}\)
a: \(x^2-4x-5=\left(x-5\right)\left(x+1\right)\)
b: \(x^2-3x+2=\left(x-2\right)\left(x-1\right)\)
d: \(2x^2-3x+1=\left(x-1\right)\left(2x-1\right)\)
k: \(4x^2-9=\left(2x-3\right)\left(2x+3\right)\)
\(\Leftrightarrow\left(3x+7\right)\left(2x-5\right)=0\)
=>x=-7/3 hoặc x=5/2
\(2x\left(3x+7\right)-15x-35=0\\ \Rightarrow2x\left(3x+7\right)-\left(15x+35\right)=0\\ \Rightarrow2x\left(3x+7\right)-5\left(3x+7\right)=0\\ \Rightarrow\left(2x-5\right)\left(3x+7\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=-\dfrac{7}{3}\end{matrix}\right.\)