First, solve 10x + y = -20 for y: y = -20 - 10x
Next, substitute -20 -10x for y in the second equation:
-20 - 10x = 2x^2 - 4x - 16.
Rearranging, 2x^2 + 6x + 4 = 0
Simplifying, x^2 + 3x + 2 = 0
The roots of this poly eqn are -1 and -2. Therefore, x = -1 and x = -2.
One by one, subst. these x-values into y = -20 - 10x to find the corresponding y-values.
Your answers should look like this: (-1, y) and (-2, y) (different values for y).
