Mental warmup (1)

$x^2 +2x=3$

$\implies x^2 + 2x - 3 = 0$

$\implies x^2 -x + 3x - 3 = 0$

$\implies x(x -1) + 3(x - 1) = 0$

$\implies (x+3)(x -1) = 0$

$\implies x=-3,1$

Sum of roots $=(-3)+1=\boxed{-2}$

Rewriting the equation in the form $ax^{2}+bx+c=0$

$x^{2}+2x-3=0$

Using Vieta's formula

sum of roots= $\frac{-b}{a}=\frac{-2}{1}=\boxed{-2}$

$(x-x_1)(x-x_2)=x^2 - (x_1+x_2)x+x_1x_2$ . As the equation is $x^2-(-2)x-3=0$ , $x_1+x_2 = -2$ .

$x^2+2x = 3$

$x^2 + 2x - 3 = 0$

Using quadratic equation formula, we get

$x = -1$ and $x=3$

Hence the answer is $(-3)+1 = \boxed{-2}$