j, <=> 2x + 2 = 5x - 7 <=> -3x = -9 <=> x = 3
k, 2x + 6 = 0 <=> 2x = -6 <=> x = -3
l, <=> 4x + 2 - 3x + 6 = 12 - 8x -12x
<=> x + 8 = -20x + 12 <=> 21x = 4 <=> x = 4/21
v: =>x+2010=0
hay x=-2010
r: =>3x+3=2x-4
hay x=-7
r: =>\(7\left(x-2\right)^2-4\left(x+1\right)^2=3\left(x^2-10x+24\right)\)
\(\Leftrightarrow7x^2-28x+28-4x^2-8x-4-3x^2+30x-72=0\)
=>-6x-48=0
hay x=-8


