2x+y = -5. Solve this for y. We get y = -2x - 5. Find y^2: 4x^2 + 20x + 25. Substitute 4x^2 + 20x + 25 for y^2 in the first equation:
x^2 + 4x^2 + 20x + 25 = 25
Then 5x^2 + 20x = 0, so that x = 0. Subst. 0 for x in the 2nd eqn and find the value of y. Write your solutions as shown above: ( , ) and ( , ).