Answer :
So if you're solving by substitution, one equation must be in slope intercept form. Ill just go with the first one.
-4x+y=6
+4x +4x
y=6+4x
Now substitute the value of y in for the value of y in the second equation:
-5x-(6+4x)=21
-5x-6-4x=21
-9x-6=21
+6 +6
-9x=27
-9 -9
x=-3
Now input that into the first equation:
-4(-3)+y=6
12+y=6
-12 -12
y=-6
I HOPE THIS WAS HELPFUL! If it was, please rate my answer!
-4x+y=6
+4x +4x
y=6+4x
Now substitute the value of y in for the value of y in the second equation:
-5x-(6+4x)=21
-5x-6-4x=21
-9x-6=21
+6 +6
-9x=27
-9 -9
x=-3
Now input that into the first equation:
-4(-3)+y=6
12+y=6
-12 -12
y=-6
I HOPE THIS WAS HELPFUL! If it was, please rate my answer!
[tex] \left \{ {{-4x+y=6} \atop {-5x-y=21}} \right. \\\\ \left \{ {{y=6+4x} \atop {-5x-y=21}} \right. \\\\Substitute\ first\ equation\ into\ the\ second\\\\
-5x-(6+4x)=21\\
-5x-6-4x=21\\
-9x-6=21\ \ \ |add\ 6\\\\
-9x=27\ \ \ |divide\ by\ -9\\\\
x=-3\\
y=6+4*(-3)=6-12=-6\\\\ \left \{ {{y=-6} \atop {x=-3}} \right. [/tex]
