(x-2)(x-1/2)=x^2-1/2x+1
-10(x^2-1/2x+1)=-10x^2+5x-10
(x-2)(x-1/2) can be multiplied by other numbers to get the middle coefficient because the coefficient of the x^2 term (p) and the constant (r) are the same from the original expression (x^2-1/2x+1).