Addition of Polynomials : SAT LEVEL 2

$$(3x + 2)^2 + (3y+4)^2 = 0$$ What is $y+x$?

The answer is $-2$. Id like to know how. Thank you.

• For future reference, algebra is fundamentally different from linear algebra. Sep 12, 2015 at 20:23

In order for the two squares to be $0$. Both expressions $(3x+2)^2$ and $(3y+4)^2$ have to be $0$.
$$3x+2=0$$ $$3y+4=0$$
Add Both equations $3(x+y)+6=0$. I leave the rest to you.
• They can only be 0 and not compensating each other (-a and +a) because they are squares and thus $\ge0$