Question

find all solutions of the system.

y+x^2=-5x
y-5x=25

Answer 1

from the 2nd:

y = 5x + 25
sub into the first

5x+25 + x^2 = -5x
x^2 + 10x + 25 = 0
(x+5)^2 = 0
x+5 = 0
x = -5

then y = 5(-5) + 25 = 0