Question

(06.02) What is the solution to the following system of equations? y = −x2 − 5x − 4 y = −x2 + 9x − 18

Answer 1

I want to solve it in a simple way: let's combine the right side of the two equations together(since they are all equal to y) we could get:

$- x^{2}-5x-4=-x^2+9x-18$, remove $-x^2$, we have:

$14=14x$, then we have: x=1

Then we have y = -1-5-4=-10, we could also test our result by put x=1, y=-10 into the second equation, and turns out the result is right.