Ask your own question, for FREE!
Mathematics
OpenStudy (anonymous):

solve 3x-4y=-4 over x+2y=-8

OpenStudy (anonymous):

I don't understand what's being asked.

OpenStudy (anonymous):

3x-4y=-4 x+2y=-8

OpenStudy (anonymous):

there's not enough information being shown

OpenStudy (shadowfiend):

That is enough information. I assume you're trying to solve for x and y.

OpenStudy (anonymous):

i agree ^^

OpenStudy (shadowfiend):

So the first step in these situations is ideally to try to get one of the variables in terms of the other. In this case, we'll try to get \(x\) in terms of \(y\). We'll pick the second equation because it's slightly easier: \[\begin{align} x + 2y &= -8\\ x &= -8 - 2y \end{align}\] So far, so good. We can now plug in for \(x\) in the first equation: \[3(-8 - 2y) - 4y = -4\] Now we can solve for \(y\): \[\begin{align} -24 - 6y - 4y &= -4\\ -24 - 10y &= -4\\ -10y &= -4 + 24 = 20\\ y &= \frac{20}{-10} = -2 \end{align}\] So we now know that \(y = -2\). We can plug \(y\) back into our equation for \(x\) and get \(x\): \[x = -8 - 2y = -8 - 2(-2) = -8 + 4 = -4\] Now we have that \(y = -2\) and \(x = -4\), but, we should plug back into both of the original equations to make sure that our result matches the equations: \[3x - 4y = 3(-4) - 4(-2) = -12 + 8 = -4\] That one matches. \[x + 2y = -4 + 2(-2) = -4 - 4 = -8\] And so does that one. The solution is right! Hope that helps.

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Latest Questions
24kGloxkzz: How Are You Guys Doing Todayy!
just now 2 Replies 0 Medals
24kGloxkzz: what is 7x + 12
3 minutes ago 0 Replies 0 Medals
WendyMorales2007: can somebody help me if they may
8 minutes ago 15 Replies 1 Medal
WendyMorales2007: What is the process of subduction
17 minutes ago 4 Replies 1 Medal
xxcoffee: congrats on purple @TWALKER16..u dezerve it
15 minutes ago 3 Replies 0 Medals
XxDeadxX: Did you know ice cubes float in there own blood
15 minutes ago 15 Replies 0 Medals
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!