Connect with experts and get insightful answers to your questions on IDNLearn.com. Get accurate and comprehensive answers to your questions from our community of knowledgeable professionals.

solve each system using elimination
x-3y=27
3x-3y=39


Sagot :

Divide the problem into 3 steps. 1.Eliminate one variable. 2. Solve for the remaining variable. 3. Use that information to solve for the second variable.
1.
Multiply the top equation by -3
-3x+9y=-81
3x-3y=39
If you add these two equations together, you are left with
6y=-42
2.
Solve for y by dividing both sides by 6
y=-7
3.
Plug -7 in for y in the either equation. I'll use the top one. It's just simpler.
x-3(-7)=27
x=6

Check your work plugging both variables into both equations to see if they are still true.

[tex]x-3y=27 \ \ \ |\times (-1) \\ 3x-3y=39 \\ \\ -x+3y=-27 \\ \underline{3x-3y=39 \ \ \ \ \ } \\ 3x-x=39-27 \\ 2x=12 \\ x=\frac{12}{2} \\ x=6 \\ \\ x-3y=27 \\ 6-3y=27 \\ -3y=27-6 \\ -3y=21 \\ y=\frac{21}{-3} \\ y=-7 \\ \\ \boxed{(x,y)=(6,-7)}[/tex]