Find the root of x^2-11x+28=0 .

 Soln:- Given that x^2-11x+28=0

Then x^2-(7+4)x+28=0

x^2-7x-4x+28=0

x(x-7) -4(x-7) =0

(x-4)(x-7) =0

(x-4) =0 or (x-7) =0

x=0+4 or x=0+7

x=4 or x=7

Hence root of given equation are 4 and 7.