Check whether the following are quadratic equations: (i) (x+1)=2(x-3) (iii) (x-2)(x+1)=(x-1)(x+3) (v) (2x-1)(x-3)=(x+5)(x-1) (vii) (x+2) = 2x(x 1) (ii) x-2x=(-2)(3-x) (iv) (x-3)(2x+1)= x (x+5) (vi) x+3x+1=(x-2) (viii) x-4x-x+1=(x-2)