Question

solve for the x value of the solution solve by substitution. -3y+3=x 9x-7y=-7

Answer 1

The first equation tells us that \(x=-3y+3\). So, we can substitute that value in for \(x\) in the second equation, which will give us:
\[
\begin{align}
9(-3y+3)-7y&=-7\\
-27y+27-7y&=-7\\
-34y+27&=-7\\
-34y&=-34\\
y&=1
\end{align}
\]
Now that we know that \(y=1\), we can plug that back into our equation to find \(x\).
\[
\begin{align}
9x-7(1)&=-7\\
9x-7&=-7\\
9x&=0\\
x&=0
\end{align}
\]
To double check our work, let's try plugging in our results into the other equation, \(x=-3y+3\). Sure enough, we get \(0=-3+3\), which is correct.

Answer 2

huh? im so lost

Answer 3

Which part did you get lost at?

Answer 4

lol the beginning

Answer 5

Basically, the idea behind substitution is that if we know what a variable equals in one equation, we can use that in the other equation. So, the first equation tells you that \(x=-3y+3\). Even though that isn't a number like we're used to plugging into a variable, we can just plug that entire expression in for \(x\). So, in the other equation, I took the \(x\) out and just replaced it with that entire expression. Does that make sense?

Answer 6

i guess ill try it on another probaly thank you

Answer 7

ok so this is a little diff. x+7y=-2 3x+y=34 so its 3(x+7y)=-2+34

Answer 8

Not quite. You have to isolate a variable first. In your other question it was a bit easier because it was already done for us. In this one, it tells you that \(x+7y=-2\). From that, we can get that \(x=-7y-2\). Now that we've isolated the \(x\), we can substitute that in for \(x\) in the other equation, which will give \(3(-7y-2)+y=34\).

Answer 9

oh i for got that step

Answer 10

x=12

Answer 11

omg your the best

Answer 12

Glad I could help ;)

Answer 13

me to that other guy hero was pissing my of so i blocked him

Answer 14

where are you from?

Answer 15

Sunny California =)

Answer 16

cool im florida

Answer 17

in florida

Answer 18

Yay hurricanes :P

Answer 19

Havent had one in 4 or more years. lol :) you have earthquakes. lol what orgin is bouscal never heard of it.

Answer 20

French

Answer 21

ooo lol