The equation of the circle whose diameter is the common chord of the circles; `x^2+y^2+3x+2y+1=0` & `x^2+y^2+3x+4y+2=0` is: `x^2+y^2+8x+10 y+2=0` `x^2+y^2-5x+4y+7=0` `2x^2+2y^2+6x+2y+1=0` None of these