[tex]3a)\\\\ (3x-4)(4x+8)=0 \\\\3x-4=0\ \ lub\ \ 4x+8=0\\\\3x=4\ \ lub\ \ 4x=-8\\\\x=\frac{4}{3}\ \ lub\ \ x=-2[/tex]
[tex]b)\\\\ \frac{2x-6}{4x+5}=\frac{4x+3}{8x-1}\\\\4x+5\neq 0\ \ i \ \ 8x-1\neq 0\\\\4x\neq -5\ \ i\ \ 8x\neq 1\\\\x\neq -\frac{5}{4}\ \ i\ \ x\neq \frac{1}{8}[/tex]
[tex](2x-6 )(8x-1)= (4x+5)(4x+3)\\\\16x^2-2x-48x+6=16x^2+12x+20x+15\\\\16x^2-2x-48x -16x^2-12x-20x=15-6\\\\ -82x=9\ \ |:(-82)\\\\x=-\frac{9}{82}[/tex]
[tex]c)\\\\x^2+2x-15=0\\\\a=1,\ \ b=2,\ \ c=-15\\\\\Delta=b^2-4ac=2^2-4*1*(-15)=4+60=64\\\\\sqrt{\Delta}=\sqrt{64}=8\\\\x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-2-8}{2*1}=\frac{-10}{2}=-5\\\\x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-2+8}{2*1}=\frac{6}{2}=3[/tex]
