Determine the nature of roots of the following quadratic equations:
(i) `2x^(2)+5x-4=0` (ii) `9x^(2)-6x+1=0`
(iii) `3x^(2)+4x+2=0` (iv) `x^(2)+2sqrt2x+1=0`
(v) `x^(2)+x+1=0` (vi) `x^(2)+ax-4=0`
(vii) `3x^(2)+7x+(1)/(2)=0`
(viii) `3x^(2)-4sqrt3x+4=0`
(ix) `2sqrt3x^(2)-5x+sqrt3=0` (x) `(x-2a)(x-2b)=4ab`