(1)x^2-4x=1
x^2-4x-1=0 a=1,b=-4,c=-1
x={-(-4)±√[(-4)²-4*1*(-1)]}/(2*1)
={4±√[16+4]}/2
={4±√20}/2
={4±2√5}/2
=2±√5
(2)3x^2+4x-1=0 a=3,b=4,c=-1
x={-4±√[4²-4*3*(-1)]}/(2*3)
={-4±√[16+12]}/6
={-4±√28}/6
={-4±2√7}/6
=(-2±√7)/3