ad2(axb+2cd)x+bc2=0
⇒a2d2x2b+2cad2xd+bc2=0
⇒a2d2x2b+2cadx+bc2=0
⇒a2d2x2+2abcdx+b2c2=0
⇒(adx+bc)2=0
⇒(adx+bc)=0
⇒x=−bcadx=0
hence proved
Show that x = -1 is a zero of quadratic equation x2– 2x – 3 = 0