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

Question

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

triciaal · Answer

set the y's equal and solve the  equation to get the  x-value.
use the x value in either expression for y to get the corresponding y-value.

bunny12 · Answer

Yes in other words, substitute the y

blowery · Answer

-x^2 - 5x - 4 = -x^2 + 9x - 18
The negative x squared will cancel out leaving
-5x - 4 = 9x - 18
Next, move the -5x to the other side of the equal mark,
-4 = 14x - 18
Next, move the -18 to the other side of the equal mark leaving
14 = 14x
Divide through by 14 leaving
1 = x
Now, substitute the 1 for x in the equation y = -x^2 - 5x - 4
Y = -1^2 - 5(1) - 4
y = 1 - 5 - 4
y = -8

triciaal · Answer

be careful with the simple stuff  
-1-5-4 = -9