The substitution method is a technique for solving a system of equations. This article reviews the technique with multiple examples and some practice problems for you to try on your own.
Log in Matt 7 years agoPosted 7 years ago. Direct link to Matt's post “I am curious if there are...” I am curious if there are times when either the elimination method or the substitution method would be more appropriate, and or if there would be times when only one way or the other would work. Thank you for the advice in advance! • (54 votes) Matthew Johnson 7 years agoPosted 7 years ago. Direct link to Matthew Johnson's post “Yes, both equations will ...” Yes, both equations will always work, but yes, at times it is more logical to use one over the other. for instance: we see here that elimination would best fit: or: substitute (2y-3) for x. Also, once you have a single placeholder, put it ito quadratic form (ax^2+bx+c=0) (38 votes) David 4 years agoPosted 4 years ago. Direct link to David's post “This is pretty challengin...” This is pretty challenging not gonna lie • (56 votes) Faeth, Laura P2 3 years agoPosted 3 years ago. Direct link to Faeth, Laura P2's post “If you practice a lot and...” If you practice a lot and have a good teacher, it'll get less challenging. (17 votes) Nancy Crisp 4 years agoPosted 4 years ago. Direct link to Nancy Crisp's post “how do I solve y=2x-1 and...” how do I solve y=2x-1 and y=3x+2 using the substitution method • (8 votes) hmd1114 3 years agoPosted 3 years ago. Direct link to hmd1114's post “You would set them equal ...” You would set them equal to each other because they both equal "y": 2x-1=3x+2 (8 votes) kenaniah 2 years agoPosted 2 years ago. Direct link to kenaniah's post “This is so hard I can't.” This is so hard I can't. • (7 votes) Kim Seidel 2 years agoPosted 2 years ago. Direct link to Kim Seidel's post “This is the review. Star...” This is the review. Start at the beginning of the lesson. Go thru each video step by step and make sure you understand before moving to the next one. Ask specific questions when there is some part of the video that you don't understand. As you do the practice problems, if you get one wrong, use the hints to learn from your mistakes. Then, come back and try the review again. (14 votes) Theo Lesko 4 years agoPosted 4 years ago. Direct link to Theo Lesko's post “are there any easy tips o...” are there any easy tips or tricks i can use to remember this? • (10 votes) joshh 10 months agoPosted 10 months ago. Direct link to joshh's post “Practice Solutions:Firs...” Practice Solutions: First system of equations: 1st equation: -5x + 4y = 3 Substitute for x: Solve for y: Solve for x by substituting in one of the equations: Check your solution by substituting for x and y in the first equation: -5x + 4y = 3 Second system of equations: 5x - 7y = 58 y = -x + 2 Subsitute for y: Solve for x: Solve for y by substituting in one of the equations: Check your solution by substituting for x and y in the first equation: 5x - 7y = 58 I hope this could help someone. It seems like a lot, but once you understand the steps and get the hang of it, it will become pretty quick! • (10 votes) LeeAnn Morales 9 months agoPosted 9 months ago. Direct link to LeeAnn Morales 's post “Lol this is actually kind...” Lol this is actually kind of simple, though it takes a different mindset. I like to think of the first equation as the problem I'm trying to solve and the second as a hint. See the second one says what x equals even if it doesn't necessarily give you the answer. Because it doesn't give the answer for y, we have to replace the x with the second equation to be able to solve for it. After solving for y, you would plug y into one of the two original equations and solve for x the way you did for y. After you solve for x, you would have the two answers you needed, x and y :) (I hope this was helpful, sorry if it wasn't :[ ...) • (8 votes) parsopey000 24 days agoPosted 24 days ago. Direct link to parsopey000's post “I know! Once I got how to...” I know! Once I got how to solve the equations it was so fun just getting through it. (2 votes) CleverDesire 3 years agoPosted 3 years ago. Direct link to CleverDesire's post “If i may ask,could anyone...” If i may ask,could anyone help me in this equation: 3y+2x=7 Please answer the question in with explaination.thanks🙏🏽🥺😊 • (4 votes) Kim Seidel 3 years agoPosted 3 years ago. Direct link to Kim Seidel's post “I'll get you started.Tak...” I'll get you started. Hope this helps. Comment back if you have questions. (8 votes) Jaiden Galecki a year agoPosted a year ago. Direct link to Jaiden Galecki's post “who is up for quiz one” who is up for quiz one • (8 votes) Emmery 4 years agoPosted 4 years ago. Direct link to Emmery's post “In example 2, when it say...” In example 2, when it says we have to solve for x or y, how do I get -2x+y=9 into slope intercept form? And also, how did we get rid of the negative once it was in slope intercept form? • (5 votes) David Severin 4 years agoPosted 4 years ago. Direct link to David Severin's post “You cannot get rid of neg...” You cannot get rid of negatives if they are there, so let the signs work themselves out. To isolate the y, all you need to do is add 2x on both sides to get y=2x+9. (6 votes)Want to join the conversation?
x-4y=6
x+4y=12
x+x+4y-4y=6+12
x=2y-3
7x+3y-81=23
and use the quadratic formula:
x=(-b±sqrt(b^2-4ac))/2a
2nd equation: x = 2y - 15
-5(2y - 15) + 4y = 3
-10y + 75 + 4y = 3
-6y = -72
y = 12
x = 2y - 15
x = 2(12) - 15
x = 9
-5(9) + 4(12) = 3
-45 + 48 = 3
3 = 3 √
5x - 7(-x + 2) = 58
5x + 7x - 14 = 58
12x - 14 = 58
12x = 58 + 14
x = 72/12
x = 6
y = -x + 2
y -(6) + 2
y = -4
5(6) - 7(-4) = 58
30 + 28 = 58
58 = 58 √
y-3x=6
Take the 2nd equation and add 3x to both sides to isolate "y".
y = 3x+3
Now, substitute this value of "y" into the first equation.
3(3x+6) + 2x = 7
You can now solve for "x".
Once you have the value of "x", use it to calculate the value of "y".
Thanks
