[ilkirby]

I need help with by elimination solving
-x -3y=-1
3x+3y=9

solve by substitution
y=11 -3x
-2x + y=1

[JudyKayTee]

You need to do the problem yourself and then post your answer. What did you get for the answer?

[wallykap]

-x -3y = -1 mult by -1 x +3y = 1
solve for x x = 1 - 3y

3x + 3y = 9 sub x 3(1 - 3y) + 3y = 9
expand 3 - 9y + 3y = 9
combine 3 -6y = 9
solve for y -6y = 9 - 3
-6y = 6
y = 6 / -6
y = -1

therefore if y = -1, then -x -3(-1) = -1
-x + 3 = -1
-x = -1 -3
-x = -4
x = 4

checking -(4) - 3(-1) = -1
-4 - (-3) = -1
-4 + 3 = -1 and

cking 3(4) + 3( -1) = 9
12 +(-3) = 9
12 -3 = 9

walt !

[wallykap]

problem #2

y = 11 -3x and -2x + y =1

sub y into second -2x + (11 -3x ) = 1
expand -2x + 11 - 3x = 1
combine -5x + 11 = 1
sub 11 -5x = 1 - 11 = (-10)
div by -5 x = 2


therefore y = 11 -3(2)
y = 5

and -2(2) + 5 = 1
-4 + 5 = 1

answers check !